Compared to the Everex $199 offering, the Shuttle one is a bit, ah, thin on features. Nice case, true, but no optical drive, which seems like a poor trade-off. I suspect the difference in features at the same price is made mostly of Windows XP, though details are at this time very hard to come by.
Right now; my money would go towards an Everex machine, weaker processor and all. It's more like a "traditional" PC and the Linux on it serves just fine, by all accounts. XP is something of an unneeded option in this class. Potential be damned. Real capabilities count for more.