9800 Pro & FS2004

Hi all
I just bought Radeon 9800 Pro and is running almost excellent. "Almost",
because I have a problem running FS2004. The fps is very low and during
(only) fs2004 harddrive is accessed constantly. It's happening on high
settings. When I minimize them, the FS2004 runs smooth with occasional
stutter once every 10-20 seconds, and harddrive is not being accessed
constantly then. I think that 9800 Pro should handle every current game
pretty easily, and my system is not so old. Any ideas, I think it's a common
problem. I've seen many posts on this topic in the past (not on this group),
but never found any solution.
BTW, during Mafia, all settings on max runs smooth with occasional stutter.
When I disable sound in Mafia's Setup the stutter no longer exists.
Disabling sound in FS2004 doesn't help at all though .

I think I got 2 problems: 1. occasional stutter (probably sound card etc) 2.
constant hd access during FS2004 (probably not sound card related)

FS2002, on maximum settings, runs (almost) beautifully if it wasn't for that
occasional stutter.

Please help, cause I thought that with this card all my gaming problems
would disappear.
Previously I had nVidia G4 420 MX, and FS2004 run almost the same as on 9800
Pro. All other games were of course much worse.
My comp:
Dell Dimension 8250
chipset Intel i850
Pentium 4 2.4 (not HT)
512 Ram
120Gb 7200
Radeon 9800 Pro 256Mb
Sound Blaster Live!