My GeForce 8500GT works well and gives acceptable, not outstanding, frame rates for most applications (easily maintains 24fps in FS9 anywhere except hi-res/congested areas like Heathrow).  But it's always had some graphics anomalies on this system which numerous forums, including nvidia, have been unable to solve.  And since Vista "upgraded" to SP2, DVD playback has not been as sharp as before.

So I've finally decided to stretch my budget and try a different card, but that budget is severely limited.  Looked at an HD4850 or GeForce 9600GT, each now available for around $70.  Reviews and comparisons give no distinct performance advantage to either.  So, while I'm taking a chance that a new card will alleviate the graphics oddities, which of these cards (or any recommendations in the same price range) would give the most performance boost over the 8500GT?

FS9, GTR2, and Morrowind are the worst resource hogs I'll be throwing at this.  (The latter, with hi-res textures and extended towns, will drag the 8500 to single digit frame rates.)

System is Vista Home Premium 32 SP2, Athlon 2.2+ dual core, 2gig, X-Fi Fatal1ty Pro, 450W PS