2 gig of RAM is plenty for Win8. Yesterday I just upgraded my wife's Netbook having 2 gig of RAM and a small Atom CPU from XP to Win 8 and it not only runs, but runs quite a bit peppier than with XP. Win8 is actually quite a nice, efficient OS despite what you may hear from the h8ers. Just boot directly to the desktop and don't use the tiles. The tiles are quite nice on touchscreens, but are a nuisance on desktops.
I used to run out using XP with 4gb ram (3,5 usable) , so i would increase it. I am surprised he has 4 slots:
DDR2 PC2-5300, DDR2 PC2-6400
Memory Type: DDR2 PC2-5300, DDR2 PC2-6400, DDR2 (non-ECC)
Maximum Memory: 4GB
Slots: 4 http://www.crucial.com/upgrade/Dell-memory/Inspiron+Desktops+/Inspiron+530-upgrades.html
2GB DDR2 PC5300 PC2-5300 667 Mhz LOW DENSITY Desktop Memory http://www.ebay.com/itm/like /370556236203?lpid=82
US $20.45 FREE Standard Shipping