I take it you're new to linux. You can try a knoppix live CD which will boot linux from a CD. I think you'll also have the ability to install it if you want to. Go to knoppix.org, download the image, and burn to a CD.
I'd go with the Dell because the alienware only comes with 128mb unless you upgrade to the 7600go. You also get MCE instead of XP home. The only thing crappy about the Dell is when you have to pay for tax.
XPS M1210 Notebook: Intel Core Duo Processor T2300E (1.66GHz/667MHz FSB)
Sound Blaster Audigy ADVANCED HD Audio Software Edition
24X CD RW/DVD Combo Drive
3945 802.11a/g Wireless Mini Card
Genuine Windows XP Media Center...