What did you reformat?
If it was the main hd, and you've since reinstalled XP - your pictures are gone.
If it was a second drive (let's say "D") being used for storage, you have a chance at data recovery if nothing has been written to it yet. Recovering data is pricey. Expect no better than about a $750 fee (some charge $1500). There are some freebie apps out there, but I have no experience with them.
Whenever a customer of mine needs this service, I canvass for the best price at that moment. Google them and make phone calls.