Team Fortress 2 - FPS Problems

[redruM000]

When im playing TF2 i get an average FPS of 10-30 and, i recently started to get fed-up with it, so i started running RivaTuner to look at temp and GPU usage (among other things)
And i noticed that While playing TF2/CS:S, the gpu usage never gets above 20%.

Its getting quite annoying, since i can play Call of Duty 4 on Medium-High at 50-60 FPS, and it uses 100% GPU, so, yea.

My PC Specs:
CPU: Intel Pentium IV (3.20GHz)
RAM: 1GB DDR400 Ram
GPU: ATi HD3650 512MB (AGP)
HDD (#1): 160GB Samsung SATAI
WLAN: D-Link DWA-110
SOUND: Onboard Realtek AC'97 Audio
MBO: MSI PM8M-V
OS: Windows Se7en Beta 1 (Build 7000)

PS. This is running game all at Low

PPS. Dont just tell me to get a new PC, if I can Play CoD4 i SHOULD be able to play TF2

PPPS. Thanks in advance

EDIT: I have also tried custom configs, they change absolutely NOTHING
and, i tried running the game all on VHigh, GPU usage stays the same, FPS barely drops. WTF

[Mittens]

PPS. Dont just tell me to get a new PC, if I can Play CoD4 i SHOULD be able to play TF2

Team Fortress 2, and pretty much all Source software are VERY CPU intensive, like "They'll gobble CPU cycles faster than a homeless kid with downs can piss himself", intensive.
With such an uneven combination of your CPU and GPU performance, expect your CPU to be crying, huddled on the floor, a broken man; before your GPU even breaks a sweat.
That said, you might be able to increase performance marginally with some of the multi-threading options in game, or by disabling Hyper-Threading in your BIOS, or installing Windows Fundamentals for Legacy PC's.

[Chripper]

GeForce Release 182 That should help a fair bit, but yes as Mittens said source games rely on a lot of scripts, and a lot of CPU power, duel cores and quad cores usually don't help as TF2 doesn't have very good multi core support, (YET) Apparently they're working on a fix for that quite soon.

[silencer.]

The fact you have a pentium 4 still is why your fps is so horrid.