the iis on a winxp cd is usually asp 1.0, current (up to date) asp.net is like 1.1 i believe so you need to check if they match up or not, just google iis upgrade 1.0

make sure that iis has the same version of asp.net as yer vs does.
are you running it against a database? did you stick a config file in the same directory for debuggin?

wont winxp pro be able to do it too? (though not as nice?)