Upgrading for FS2004

Hello,I currently have a P4 2.4 GHz, 512 Mb DDR 266 MHz and a GF4 Ti4200 128MB.I am thinking about upgrading my graphics card to a top of the line GeForce FX 5900 Ultra 256 MB or a Radeon 9800 Pro 256 MB.Which one do you think it is better and what improvement may I get? I currently fly in 1024x768x16 with 2x AA and 2x AF. Around 10 FPS in Overcast clouds... what can I expect with the new card, on the same settings?I've heard the Radeon cards have some issues with other games, besides FS, is that true?Also, adding more 512 Mb of 266MHz RAM make any difference in FPS? I don't have any stutters, just need more speed...Is RAM easy to install? Can I do it at home?I'd like to have these questions answered, pleaseThank you___________________________________________________ Lu