Random internet lag spikes

[EternalFlame]

Hey guys I have been having this problem since I bought my new computer about 6 months ago and ever since then I have been experiencing lag.

First off my hardware specs and stuff:
Processor: Intel core i5 quad 750@2.67GHz
RAM 8gbs
Windows 7 Professional 64-bit (6.1, Build 7600)
System Manufacturer: INTEL_
DirectX Version: DirectX 11
Card name: NVIDIA GeForce GTX 260
DAC type: Integrated RAMDAC
Driver Version: 8.16.11.9107

Im sorry I dont know what the dac type is but I figured it would help
I am also using a wireless card and my wireless router is a linksys wnt160n.
internet speed is about 5 mbts.

So what happens is when im playing online games such as css, APB, WoW, Gmod games like that I will get random internet lag spikes. (I think its internet because its a brand new computer and is very good)
But before I used this computer I had a very BAD laptop that was on the same router and it was wireless as well and I had no lag spikes. What happens is in APB for example when im driving it will keep turning left or right and I always have a second delay on turning and stuff. Also on foot I will just keep walking and all of a sudden i appear 10 feet away. I also have a computer that uses Ethernet and does not get these either. My internet does have a WEP key so no one SHOULD be leaching off my internet.
I am sorry if it seems rather vauge but im not that techy so if you need any more info please let me know.

I sure hope one of you guys can help. THANKS


OH! also my wireless card is either an intel 82578DC gigabit network connection OR a linksys wirelss-G PCI adapter. Im sorry again, I don't know much about this kind of stuff.

[GroundZero3]

Do you have the ability to plug directly into the router? Also WEP can be broken in less than a minute these days