I get 40-60 with less of a system.... ( mid 30's when really busy )
I have all set to 3 except clouds @1, and aircraft @5
1024x768x16 rez.
the biggest part is to turn off the dual render in the config , and set it to High rez ( right below that )
my system is ...
AMD1700+ XP ( 1.47)
768 pc2100
G4 Ti4200 64m
NF2S-ALH mb
Win XP pro
30g WD hd ata100 - 7200rpm
creative 5.1 live
APC ups
10m cable connection thru RR
have you checked out my tweaks file in the CFS3 Misc. page here

it helped alot of others I know.
otherwise , email me , and I will try to help you set up.
my email: raaf453-shep@satx.rr.com