I was using Radeon 9800 PRO because i was curious about its performance and hoped that it would be good, but with problems above and even some glitches in GLQuake, GLHexen 2 in WinXP i lost my patience and tried Nvidia card - slowest Geforce 4 - 4200 TI model, i dont have anything faster and Geforce 5/6 line is too new and less compatible. 
   
   I expected that performance would be much slower, i knew that Radeon 9800 could gain a lot with faster CPU, but still i expected better result in comparison with  Geforce 4200 TI, but see result bellow. I used same binaries for OSes so if it. You crashes, its not because of testing program. You can also see comparison of Win98/Win2000/XP performance. With Nvidia card my installation Windows 2000 worked fine, so it was ATI card problem, not OS problem.  Framerates values are for AVG. I had to disable Vsynch for OpenGL in Nvidia drivers, through normal setting or thanks to coolbits reg hack for drivers settings.
1) Quake 3 demo - \timedemo 1  ; remove 90 FPS cap - /Com_maxFPS 0  , inbuild demo (Demo001) in menu
   1024x768x16bit.. otherwise max details..
  PIII 1.4 + Radeon 9800 PRO - WinXP - 10.2 Drivers -  112; 32bit same results - 112.
  PIII 1.4 + Radeon 9800 PRO - Win2000 - 6.14 Drivers - Openg is not working 
  PIII 1.4 + Radeon 9800 PRO - Win98SE - 4.15 Drivers - 95
  PIII 1.4 + Geforce 4 Ti 4200 - WinXP - 93.xx Drivers - 115
  PIII 1.4 + Geforce 4 Ti 4200 - Win2000 - 93.xx Drivers - 117
  PIII 1.4 + Geforce 4 Ti 4200 - Win98 - 43.55 Drivers - 85
2) Quake 2 demo - OpenGL \timedemo 1 \map Q2demo1.dm2   
  1024x768x16bit.. max details..
  PIII 1.4 + Radeon 9800 PRO - WinXP - 10.2 Drivers - 197 
  PIII 1.4 + Radeon 9800 PRO - Win2000 - 6.14 Drivers - OpenGL is not working
  PIII 1.4 + Radeon 9800 PRO - Win98SE - 4.15 Drivers - 178 ; I had it to disable Vertical synch in ATI drivers OpenGL settings.
  PIII 1.4 + Geforce 4 Ti 4200 - WinXP - 93.xx Drivers - 222
  PIII 1.4 + Geforce 4 Ti 4200 - Win2000 - 93.xx Drivers - 217
  PIII 1.4 + Geforce 4 Ti 4200 - Win98 - 43.55 Drivers -  150
3) MDK2 demo - Texture Quality slider max, filtering - trilinear, 1024x768x16 - First 2 checkboxes. Test setting button starts benchmark.
   PIII 1.4 + Radeon 9800 PRO - WinXP - 10.2 Drivers - 109
   PIII 1.4 + Radeon 9800 PRO - Win2000 - 6.14 Drivers - generic OpenGL - slideshow
   PIII 1.4 + Radeon 9800 PRO - Win98SE - 4.15 Drivers - 140
   PIII 1.4 + Geforce 4 Ti 4200 - WinXP - 93.xx Drivers - 134
   PIII 1.4 + Geforce 4 Ti 4200 - Win2000 - 93.xx Drivers - 133
   PIII 1.4 + Geforce 4 Ti 4200 - Win98 - 43.55 Drivers - sideshow as would be generic OpenGL driver is used..
 
4) GLQuake - batch: -width 1024 -height 768 -bpp 16 -window ; after that in console: timedemo demo1
    PIII 1.4 + Radeon 9800 PRO - WinXP - 10.2 Drivers - 243  
    PIII 1.4 + Radeon 9800 PRO - Win2000 - 6.14 Drivers - Openg is not working, only generic driver Slideshow 
    PIII 1.4 + Radeon 9800 PRO - Win98SE - 4.15 Drivers - 245
    PIII 1.4 + Geforce 4 Ti 4200 - WinXP - 93.xx Drivers - 233
    PIII 1.4 + Geforce 4 Ti 4200 - Win2000 - 93.xx Drivers - 305
    PIII 1.4 + Geforce 4 Ti 4200 - Win98 - 43.55 Drivers - 209
    
5) Expendable demo (batch file: go- timedemo) - Direct3D 
   1024x768, In setup no Checkbox used; Results are in timedemo.txt file..
   PIII 1.4 + Radeon 9800 PRO - WinXP - 10.2 Drivers - 89 
   PIII 1.4 + Radeon 9800 PRO - Win2000 - 6.14 Drivers -76
   PIII 1.4 + Radeon 9800 PRO - Win98SE - 4.15 Drivers - crash
   PIII 1.4 + Geforce 4 Ti 4200 - WinXP - 93.xx Drivers - 66
   PIII 1.4 + Geforce 4 Ti 4200 - Win2000 - 93.xx Drivers - 67
   PIII 1.4 + Geforce 4 Ti 4200 - Win98 - 43.55 Drivers - crash
  
  As you can see Geforce 4200 TI is actually faster in OpenGL and only significantly slower in Direct3D - Expandable. I was not running synthetic benchmarks, because their results are often misleading and you can play them. For Win98 i used old drivers 43.55 for Nvidia, newer driver could be maybe faster for some titles - especially Quake 3, but its also known that they are slower for other titles.
  But its not so great as it could seems, because..
1) Even Win98 + Nvidia met same generic driver slideshow problem as with Win2000 and ATI card.. Even when Glinfo - showed all good Nvidia values - you really cant believe in this utility. Fortunately, i fixed it, but installing older drivers, i dunno maybe only reinstaling same driver version once more would help.. I had not patience for that.
2) Win98 -1 OpenGL game did not working, even when all other games were ok.. MDK 2 demo, it was slideshow and very,very slow loading, which here for usage Generic OpenGL driver. 
    MDK 2 demo has own setup utility, which can print OpenGL info.. that is really strange that that driver name is ended by "/ForceSW" .. what is very suspicious, but why this mode is executed.. its not explained, there is really something what we need to understand.
Im old goal oriented goatman, i care about facts and freedom, not about egos+prejudices. Hoarding=sickness. If you want respect, gain it by your behavior. I hate stupid SW limits, SW=virtual world, everything should be possible if you have enough raw HW.