SL problem between cursor, system and graphic card

[darel]

First, Hi and sorry for my basic english.
After a few installations of snow leopard by Hazard 10.6.2, everythings seems to be OK but my graphic card (Geforce 7300 go, equal as Quadro NVS 110M).

If I boot without graphic injector, graphicEnabler or EFi strings my system is OK but resolution is blocked @ 1024x768.

When I apply one of this three things to make my 7300go to work there is the same problem at reboot :
resolution 1400*900 OK but the cursor is jumpy and very, very, very fast so I can't control it. And the system lag when launchnig applications or anything else.
What I've noticed : when I launch an application the system is very very slow but my cursor run very well !!!!! and return to bad behavior when the application is launched.

What I've tried with no solution:
-different kernel : 10.0 10.2 10.3
-set my trackpad preference to the slowest movement
-applePS2trackpad or VoodooPS2trackpad
-Injectors, efi strings, graphicenabler (it recognize my card with -pci1)

I've read on a forum that it looks like an IRQ problem because it goes well when the system is trying to do something, but my knowledge is too bad about that.

Won't you please, please, help me. Help meeee oooooo