Having problems installing XP mode on my Win. 7 computer, please help?

Ok so i bought star wars kotor (knights of the old republic) and my friend says it will only run in xp mode, which is why it hasnt been working on my win 7 computer. so i go to microsoft.com and try to download it along with virtual pc, but before itll let me download, it says i need some verification thing to install on my comp. so i installed it but still everytime i try to download xp mode and virtual pc, it says i need to install the verification thing! Yes, i downloaded it and installed it, and for the right OS, Windows 7 Ultimate 32 bit, so please help! i want to play KotOR!