The best you can get is the Athlon XP 3200+ (Barton core)
Very nice stable (and fast) CPU (I've got 2 machines with 'em) - Overclocks well with reasonable cooling
Available from Kelkoo -
http://shopping.kelkoo.co.uk/b/a/ss_...n_xp_3200.html
86 quid, though you may be able to find one cheaper.
Why not stick SuSE or Kabuntu (I hate Gnome) on your doorstop and live a little?
Edited to add: They're all Socket A/Socket 462 of course