make sure you rebooted after installation. then go into sys prefs > network and acknowledge the 2 new interfaces just installed. If you dont get this, uninstall parallels, reboot, reinstall and reboot again.
forgive the ignorance, but if i uninstall and reinstall, will that do away with all my files saved on XP?
the virtual machine will not be affected by an uninstall of the parallels application. they will remain in ~/Library/Parallels until you remove them manually, which of course you dont need to do.
umm download the dmg file again from the download link at the top of the page and run the uninstaller in it.