after you install linux it should install a bootloader (if you make set it to). if a new boot loader is installed, then you can just select windows at that screen without any problems; whether errors occured with linux or not.
if your linux installation does not go well, boot your computer into your windows xp pro/home cd, select repair/recovery console, or whatever its called exactly, from the first screen after it loads for a couple moments. log into your windows installation using the admin password (needed), type 'fixmbr' and hit enter, it will prompt you yes/no to do this... then do 'fixboot' and hit enter, and it will prompt you again, accept them both. then type 'exit' and enter to reboot, or just hard boot the computer and remove the xp cd. this should make windows forget all about linux and you can give it another shot or whatever.