pls i want to know the difference and the advantage of these various amd cpu:
duron,athlon xp,sempron

The AthlonXP was AMD's main workhorse CPU. They're still the best and most powerful CPU's on SocketA, but they've since been replaced by AMD's new Athlon64 CPU's. The AthlonXP's topped out with the Barton core, which sported 512KB of L2 cache and ran on the 333MHz & 400MHz FSB's, making them very powerful for their clock speed. The new Athlon64's continue this tradition.

The Duron was AMD's old value-oriented CPU. It was, for the most part, just an Athlon or AthlonXP with less L2 cache (only 64KB) and often ran on the slower FSB's (like 200MHz & 266MHz). As AMD ramped up production of their AthlonXP's and were able to sell the slower ones at very low prices, the Duron eventually vanished because there was no point in making them.

The Sempron is AMD's new value-oriented CPU, and just like the Duron, AMD cuts a few corners to make the Sempron cheaper. First of all, Semprons are rated based on their business app performance, not overall performance, so they get higher numbers (which helps sales). Second of all, Semprons on SocketA are being produced like crazy, so the pure volume keeps them below AthlonXP prices - while on Socket 754, AMD cut out 64-bit support to keep Sempron prices below that of Athlon64's. In both cases, Semprons are kept really really cheap to ensure their survival. AMD seems to be more dedicated to keeping the Sempron around right now, but we'll see how long that lasts. While not likely, the Sempron may just end up vanishing like the Duron before it.