WinXP SP2 won't start after GeForce FX5500 plugged
I have a MoBo Gigabyte K8VM800M with an onboard graphic card that just started to fail at 1200x1024x32@60, so I bought a Gigabyte GeForce FX5500 (GV-N55256D-E) but after I plugged it WinXP just won't load, it freezes on the windows logo screen, sometimes showing from 1 to 4 vertical-aligned dots at the right of the "progress bar" -that happens even on "safe mode".
If I unplug the FX5500 WinXP starts just fine, though it's still failing at 1200x1024x32@60 so I have to set the res. to 1024x768x32@85. I also have Ubuntu64 installed, and it does work Ok with the FX5500, although it uses it as a generic card. Back on WinXP I've tried disabling the onboard card via the hardware manager with no success (still freezes at startup)
I've read somewhere to try to install the up-to-date drivers for this card, but that's quite complicated if can't even log into WinXP despite the "mode" I choose (such as VGA or Safe mode)
Any help will be appreciated.