Note: it's spelled Sempron, just to straighten that out.
Theyre better than a regular Tbred, but worse than a barton.... kinda like a "thorton", i guess.
TigerDirect had the 2800 Sempron and 2800 BartonXP at the same price... No advantage there... except the Sempron is retail...
they have lower clock speeds than the bartons though, which i thought was weird - being based on a tbred but "slower" than a barton.
I don't see any real advantage to them... unless they were dirt cheap, i would never buy one.