I agree with ChipDeath, upgrading your current setup to a 2800+ Sempron is pointless. When you consider the performance gains you could make with an XP chip (especially overclocked), you might as well be throwing $100 out the window if you buy the Sempron. It is an upgrade, however, not a very good one, especially for the same price you could have a better Athlon XP chip, that runs faster, and has more L2 cache.
When you first built your XP setup, would you have bought a Duron? Same thing here, the Sempron is the new Duron, you want something that is going to be a real upgrade, the 2800+ Sempron is not the way to go.
Sorry, I just can't recommend a SocketA Sempron over an XP chip at the moment, espeically to someone wanting to upgrade an XP chip.
My Desktop: <A HREF="http://Mr5oh.tripod.com/pc.html" target="_new">http://Mr5oh.tripod.com/pc.html</A>