Here are my computer specs:
AMD Athlon 64X2 dual core 5000+ 2.6ghz
2GB memory installed(getting 2GB more soon)
windows 7 32bit OS
OEM motherboard HP pavillion m7750n
1 PCIe slot
PSU 300W (upgrading to 550W soon)
Nvida Geforce 6150 on board
Will a gtx 260 to GTX 465 work on my system? or could i go with ATI equivalent?
Planning on playing wow cataclysm on max settings and other high end graphics rpgs
Yeah, it's not a very large card; shorter than a microATX motherboard so it should fit unless there is something odd going on with the case.
The issue is your CPU which is bit weak by today's standards. It will do alright still in most games but it is going to struggle in the more CPU intensive titles. You can't really upgrade the CPU without replacing the motherboard btw.