**EDIT:**
New problems have recently arisen. So instead of expecting people to read the old and then the new, here's a run down of all the issues currently affecting my computer:

1. Fluctuating download speeds over Wifi (upload speed is more stable)
2. Sound cuts out intermittently
3. Graphics seems to skip frames (move mouse/type, occasional lag before changes appear on screen)

This all makes me think either CPU or motherboard now. I'm leaning more towards the motherboard; it would suggest to me that the data buses are failing. On the other hand, if the CPU is messing up, I'm not sure I could tell the difference. 

Hoping someone can tell me if either of these makes sense as the root of all these issues. I'd rather not buy a new CPU/mobo and find out it's not the issue.

**Old post:**
I came back from college and brought my desktop computer. Family recently switched to Verizon FIOS and got a new router because of it. Unfortunately, my connection to the new wifi network is awful, with the download speeds (tested through speedtest.net) fluctuating wildly and often dropping below 1.5 Mbps. A laptop in the same room gets 20 Mbps. I've tried a new wireless card, thinking that mine got damaged in the move home but no luck. 

Here's where it gets weird: if I place the laptop near the computer, the laptop's download speeds often suffer greatly. Pulling the laptop away always fixes this. So now I'm under the impression that there's something in the computer (which I built a year ago and has had 0 issues up to this point) is causing an insane amount of wireless interference. 

Also bizarre: the upload speeds seem unaffected by this problem. On the laptop and desktop, upload speeds are generally around 5 Mpbs. 

Any ideas as to what could be causing this and how to test said theories would be fantastic.