The bundled drivers are bad but I get the same problem with the latest Aetheros drivers too.

It can handle constant uploads of 400 kB/s but torrents kill it dead.

Run MemTest86+ for a day - no errors.
HD is fine too.

Think it must be the wifi though why would it be a problem? How can a wifi dongle not do wifi properly?!

Delete all my threads.

First, my specs:

ASUS PQ5 Pro
Q6600
2GB Corsair XMS2
Windows XP SP3

Wifi: TP-LINK TL-WN620G latest drivers.
Router: Linksys WRT300N