Timstuff - Ditch the Sempron and slurge a bit more to buy this:
http://www.newegg.com/app/ViewProductDesc.asp?description=19-103-436&depa=1The Barton Mobile XP 2600. The processor is much more powerful than the Sempron and only costs a few bucks more. Plus you get the added advantage of overclocking the cpu up to XP3200 speeds without any issues.
The short version of the Mobile Barton story is that they are simply the best chips that come off of the Barton wafer. They are the ones that need less voltage to run at high speeds, which is important for a laptop sense voltage equals battery life. The next best Bartons become the desktop XP3200s and so on.
The other advantage of the Mobiles are that they are all unlocked because the laptops need to access the multipliers for PowerNow. So, you can set the clock speed anyway you want.
I've got two Mobile Bartons. One was a XP2400 that overclocked to 2.45 ghz in my desktop and it's now in my arcade cabinet at 2.2ghz (would've gone faster if I had faster RAM in my cab). My XP2600 is in my desktop PC and has been OC at 2.7ghz for the last year with NO stability issues.
Don't be afraid of ocing the Mobile 2600 to 2.2ghz since the exact same chip is used for the desktop 3200 processor.
Let me know if you need more info.