Hey whatsup guys I really need some help here. My computer which was custom built for gaming is getting horrible Fps or not what it should be getting. Heres my rig.

Processor:
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz (4 CPUs), ~2.4GHz

Memory:
4 gigs of 6400 channel ddr2 ram

Hard Drive:
320 GB

Video Card:
NVIDIA GeForce GTX 260 Core 216 Superclocked Edition

Operating System:
Windows Vista™ Home Basic (6.0, Build 6002) Service Pack 2

Motherboard:
ASUS P5N-D

Im getting the following fps in these games:

Crysis Warhead:
Lowest (idle: 32 fps Busy: 23-30 fps)
Gamer: (Idle: 28 fps Busy: 15-25 fps)
Overclocked GPU + Enthusiast (Idle 19 fps Busy 10-15 fps)

World Of Warcraft:
Lowest (idle 35-40 fps Busy 30-40 fps)
Highest + overclocked GPU (idle 38-42 fps Busy 31-40 fps)

Garrys mod/ Half life 2
Lowest (idle 40 fps Busy 31-39 fps)
All max (idle 36 fps Busy 28-36 fps)
All Max + Overclocked GPU (idle 38 fps Busy 30-39 fps)

I also own 3Dmarkvantage and i got the following score (Overclocked GPU)
12357 overall points
10350 GPU score
21157 CPU score

I really dont know what to do and i really hope someone will help me out here. Thanks.

PS: Just incase you missed it somehow I DO overclock my GPU somewhat high (720-730 linked core clock and 1120 memory clock) but I DO NOT overclock through BIOS i use EVGA precesion 1.7.1. My MOBO is never overclocked niether is my memory.