Dear all,I build my own system and running Windows Vista system builder license (OEM), this is the brief spec. of my system: Q6600 CPU running at 3.2 GHz, 4 GB ram and 9600GT video card.Two questions:(1) does anybody know if I can upgrade my graphic card without violating license agreement? I know I can not change CPU under this license.(2) I'm planning to upgrade to ATI 4890 card. will this upgrade help FSX performance? Thanks! Charles , KDTW

Yes you can upgrade the video card without issue. You can also upgrade your cpu without issue. The only thing that you may have an issue with would be the Mobo, but even that I don't believe becomes an issue until you are talking about W7 OEM versions.As for the specifics on the GPU I would stick with Nvidia unless you are going with the 5870 card. The majority of users that have the 4xxx series have very slow FPS with clouds in FSX and FS9. I personally experienced this with my 3850 after upgrading it from a 6800. The 4890 is running in the $200 price range right now which is the same as a GTX 260. I would either go for the 260 or look into a 275 which is just slightly more.Jeremy

Thanks Jeremy, very good advise.Charles KDTW

You could also study the EULA which should be present on the installation dvd disc to determine if it's also legal.