General

Help with high ping for Cod4 PC?

So i got CoD4 for Pc from steam for 15 dollars. my 2ed call of duty game =D and im getting 300~400 ping per game 250 if lucky. either ill lag hard in hte game, get kicked for high ping before i even choose my class, or when i get in the game ill get kicked by punkbusters.

I used Can you Run It, and ive passed the requirements of:
[i]Recommended Specs[/i]
CPU: 2.4 GHz dual core or better
RAM: 1G for XP; 2G for Vista
Hard Drive: 8GB of free space
Video card: 3.0 Shader Support recommended. Nvidia Geforce 7800 or better or ATI Radeon X1800 or better

And

[i]Minimum requrements[/i]
Required (minimum) SpecsCPU: Intel(R) Pentium(R) 4 2.4 GHz or AMD(R) Athlon(TM) 64 2800+ processor or any 1.8Ghz Dual Core Processor or better supported
RAM: 512MB RAM (768MB for Windows Vista)
Hard Drive: 8GB of free space
Video card: NVIDIA(R) Geforce(TM) 6600
or better or ATI(R) Radeon(R) 9800 Pro or better

[b]While mine is:[/b]

CPU Speed
Recommended: 2.4 GHz dual core or better
You Have: 2.80 GHz Performance Rated at: 5.04 GHz
PASS
RAM
Recommended: 1 GB (2 GB for Windows Vista
You Have: 3.0 GB
PASS
OS
Recommended: Windows XP/Vista
You Have: Microsoft Windows 7 Ultimate Edition (build 7600), 32-bit
PASS
Video Card
Recommended: 3.0 Shader Support recommended. Nvidia Geforce 7800 or better or ATI Radeon X1800 or better
You Have: GeForce 8400 GS
PASS
Features: Recommended attributes of your Video Card
Required You Have
Video RAM 256 MB 1.7 GB
3D Yes Yes
Hardware T&L Yes Yes
Pixel Shader version 3.0 4.0
Vertex Shader version 3.0 4.0

DirectX version
Recommended: 9.0c
You Have: 10.0
PASS
Sound Card
Recommended: Yes
You Have: High Definition Audio Device
PASS
Free Disk Space
Recommended: 8 GB of uncompressed free hard disk space (plus 600 MB for Windows swap file)
You Have: 207.2 GB
PASS
DVD-ROM
Recommended: 6X DVD-ROM
You Have: TSSTcorp CD/DVDW SH-S182M ATA Device
PASS
CPU
Recommended: 2.4 GHz dual core or better
You Have: Intel(R) Core(TM)2 Duo CPU E7400 @ 2.80GHz
PASS

[b]Also i use window 7 32 bit, and i reformated it 2 days ago from Xp to w7 so i shouldnt have any viruses and also i already scanned my computer.[/b]
I also thought it was my brother was lagging me but its not. i turn off his computer, and ill still hav ethe same ping of 300~400 ping