I notice that NewEgg.com has a bunch of memory on sale. Currently I have 2gb (800MHz) with WinXP Pro SP2. If I add another 2gb, will FSX make good use of it? I remember when FSX first came out there was a series of long threads about tricking WinXP into using more memory, but the consensus seemed to be that it wasn't stable.

I don't know, but you may want to read this link about OOM errors:http://www.simforums.com/forums/forum_posts.asp?TID=21490

IF you are over clocking adding 2 more Gigs would mean, you may have to throttle down the OC. I learned this the hardway. I retured the 2Gig additional (I now have only 2 Gigs) because I was not prepared to turn down the Memory speed that I was forced to do when I added to 4Gigs.Manny

32 bit windows (if you don't know then you have 32bit) can use4G of memory.A single application can ONLY use 2Gbyte of memory (the rest is usedby other apps, OS, drivers, and shadow of GPU memory).Can FSX use more than 2g - no, but there may be a little improvementas other things can take real memory rather than paging. It is generally recommended not to bother more than 3Gbyte of memory withwindows 32bit OS (either Vista or XP).You will do more making sure the speed of your memory is matchedwith your mobo and as fast as possible.Tom