When I download anything, net stops working.

I just recently purchased a new Linksys WRT54G2 V1.

Everything works fine though when I download a big file usually over 100MB as any movie from iTunes is my internet stops working and my downloads stop as well. I disable my network in windows network properties and re-enable it and then it will work again for about another 100MB's or so only to find the same problem again.

This only happens when I use the wired connection, the wireless continues to work so I don't know whether it may be the port I'm using or my computer.

Are there any resources that I can teach me more about my router settings? Maybe the problem lies in the router's software?

I never have this problem when using a torrent application such as Blizzard's Torrent App.

I also recently upgraded the processor and video card from...
P4 3.0 GHz & ATi X850XT
to
Core2Duo E7500 & ATi Radeon HD 3850
I don't think any of those upgrades have anything to do with my network at all, but mayyyyybe. idk

Help? Thanks!