first of all,
i was running ONLY Xolox on my windows XP PRO (P4, 1Ghz, 256 MB DDR) and it STILL managed to freeze up my system after keeping it running for about 10 minutes.

exactly the same thing happend with windows 98 !
what it did, was sending huge uploads while my downloads where a miserable 5 kbps maximum!

this is NOT normal behaviour and is NOT due to their server or whatsoever.

how else do you explain other filesharing programs (morpheus, kazaa, edonkey) who basically use the same method, but will never boost your upload without your knowledge or approval?

oh, and please spare me the spyware-excuse.
that's what AD-aware is for.