11-01-2012, 04:27 PM
From the specifications you've listed I see no reason for you to upgrade *except* for the fact that XP is no longer going to be receiving security updates. Even so, I would say that Win7 32bit would be your best upgrade. Win8 isn't for desktops, it's for mobile/tablet.
Hardcore Diablo 1/2/3/4 & Retail/Classic WoW adventurer.