Need to know yer processor too; chances are you'll need a quadcore for 5boxing if you don't want it to melt :p

Ram looks fine, OS is fine, Vidcard I'm unsure of...I have a 7900 myself and 3 runs fine for me too but I have half your ram and a dualcore processor. If yer processor is any good or you can get a nice quadcore cheap you should be fine for 5boxing