You may have issues finding a good comparison. I believe the Geforce 6150SE is integrated graphics and the 4350 is an actual video card. You are basically looking to upgrade from onboard to a discrete video card. The difference between these two is so astronomical it doesn't REALLY deserve a comparison.
What is your reason for upgrading? We can help guide you through the best discrete video card for your need. However, anyone here will tell you that going from onboard video to ANY expansion card has ALOT of benefits. Are you looking to game, video editing, higher resolutions, or just better over all graphics?