PCs with XP are still available in the UK - on the suggestion of a friend I purchased a desktop from UK based e-buyer.com (
http://www.ebuyer.com/) last week.
There are (as I recall) around 50 desktops with XP available, and I imagine a worthwhile selection of Laptops. (search the "Business PCs" section)
My PC arrived on the date promised at a very competitive price... and with very little third party software (crapware!) on the machine... and very easy to get started as well.
I am vey pleased with the purchase, worth a look in my opinion.
Martin