I do it all the time.
i7 2600k, slightly overclocked
8 gig ram
all settings maxed to ultra, none lowered anywhere
30 " screen 2560 x 1600
SLI GTX 670s no overclocking
20/5 FIOS connection
using both a CM/WW Wizard and a Whirlwind Barb (never disconnected once so far either) solo and in 2-3 player game with friends
Do you play with sound enabled, and music?