Ah, while looking online, almost everywhere in the US and the UK will have them listed as 700c, then shoot for a 25-32 width.
You'll also want to get the appropriate valve length. How deep are your rims? Oh, and valve type as well. Probably presta, but they do make Schraeder 700c tubes also.
Last edited by LesterOfPuppets; 04-19-10 at 05:47 PM.