Project AI.....they're all around you!! So comprehensive, and constantly growing. Makes your airports come to life, albeit with a bit of a frame-rate hit at large airports!! Best of all, it's totally free!!FS Genesis Europe mesh is great!TTools and AFCAD 2 should surely be high on many peoples' lists...not strictly add-ons, but invaluable to making FS9 what YOU want!The RealAir Spitfire...Mmmmmmm...gorgeous!IFDG and POSKY, and SGA/Kittyhawk 737NG...superb!!Eric Marciano's A320/A330 panels...first class freeware panels!Rok Dolonek's (spelling??) KC-135, with my customised HJG 707 panel (customised extensively to look much more like the KC-135R panel - virtualy unrecognisable as the HJG original!!).The HJG KC-135 with the above mentioned panel....PMDG 737, and PSS A320/A330-340 Pro...UK2000 series airports, including Heathrow Pro (even if it does slaughter frame rates!!)My new Saitek X52 joystick/throttle controller.The numerous AFCAD 2 files that have filled otherwise empty airports with AI...The above are the most important and favourite must-have's for me, in no particular order of preference.

The one single program which increases the feel of FS9 by the largest amount is Activesky.No other single program makes such a large difference to the reality of FS9.Combine that with Skyworld and you have an incredible package to revolutionize the way FS9 looks and flies.Darren

I forgot to mention FSSkyWorld ... anther great addon that someone mentioned earlier. I too use it alongside Activesky and the results are stunning - particularly dusk/dawn shots.FSUIPC as was mentioned is the hidden treasure alright - it is truly an amazing piece of functionality that probably isn't realised as much as it should. What's more impressive is the length of time it has been with us.Also worth a mention for me is UK & Ireland Roads ... it's subtle but visually adds that little bit extra. Tie that in with FSGlobal2005 and reality comes closer.That's the the other aspect of addons -> on their own they are impressive, but marry various scenery and texture addons together and the results can be overwhelming. Which takes me onto freeware essentials - of course FSW clouds, lennart season textures, Gerrish trees, Airport environment, but to mention a few. And some of the freeware soundsets available are just incredible.Where would we be without such expandability. For me that is the single biggest attribute that makes FS9 a powerful simulation. It's a giant recipe with so many variations and configurations flying around throughout this wonderful world of ours.I remember the first addon that left me in awe, for FS98 and it was EFIS98 ... I was amazed ... anyone remember that?Anyway - thanks for all the replies guys. I would start a "worst addon" with A320PIC topping the lists BUT, I wouldn't like to upset anyone ... not least of which is AVSIM.And where would we all be without AVSIM ... It's not an addon, but it's single most invaluable simulation accessory (if I can call it that) around.

"It's a giant recipe with so many variations and configurations flying around throughout this wonderful world of ours."Yup it's the sheer number and diversity of the addons that finally won me over from the FU3 and X-Plane camps. In the past FS was always a bit like jack of all trades. FU3 was still better for VFR flights (which is what I mainly do). However with the advent of VFR GA aircraft in their dozens and VFR sceneries like Misty Fjords, Megascenery, Swiss Pro, England and Wales VFR and more this changed in a big way.

JimmiG,You are right. MSFS is more accomplished as a simulator now - it has evolved and matured well which is the primary reason it leaves the competition standing (IMHO). I toyed with XPlane some time ago, and I was impressed, but although scientifically it's (arguably) more advanced than MSFS, it just feels that bit more detached from reality.I do have one small gripe though, but it's more a Microsoft gripe than FS, they do tend to be buggy at times (and I include their OSs). I wish stutters could be banished forever ... I'm dreaming now! I remember fs98 which I enjoyed tremendously at the time, FS2000 which was a dog, FS2002 was a huge step forward but needed technology to catch up, and now FS9 which has superb technology (if you can afford it) to utilise.Still, I started simulations on a spectrum 48k ... even then I was encapsulated ... I was bitten a long time ago!

Definitely Traffic 2004 and ActiveSky.

Yes I agree that FS Navigator is the number one enhancer. Also, FSGenesis Mesh and Landclass files.

I hope I dont forget anyone here!1. Freeware scenery by Justin Tyme & Holger Sandmann. Their mesh has *transformed* the FS9 world for me. Thanx guys, u rock :)2.iFDG for their wonderful A319, A320 & A321 & 767-300.3.Posky for their 7574.AFG for their PC-12 and mind-blowing YS-11. And on a side note: whoever created those RR Dart sounds needs a medal!5. Meljet for his wicked 777! (Thanks also to the creators of GE90, RR Trent & PW engine sounds for this heavy jet)6. The author of Almaty(sp?) airport in Kazakhstan. Freeware add-on but wow wow wow! 7. Project AI - what can I say the work of these people has at last upped the realism in FS9s airports for me. Bye bye empty Heathrow...now I got hordes of airplanes trundling around! Yay! 8. Chris Arrington for his night-scenery & airport environment upgrade9. Ken Mitchell for his panels!10. PMDG - I bit off way more than I could chew when I bought this as Im not into complex ultra-real simming but I can tell the depth of this work! I now fly their planes using a freeware panel I downloaded to make their complex 737 a FS9-style "get-up-and-go" plane!11. Lennart for his texture replacements12. All the other freeware people out there whom I cant remember at this time. You know who you are - ThrottleUp is grateful.:)

1: trackir+vectorexp.2: trackir+vectorexp.3: trackir+vectorexp.4: trackir+vectorexp.5: trackir+vectorexp.6: trackir+vectorexp.7: never mind..