Xp to Win 7 Please HELPPP

Alright so i have windows 7 upgrade and im building a new PC, i dont want to buy the full version of Win 7. I have Win Xp running on my current PC i have the Product key but i dont have the disk. Is there some way of putting Win Xp into my new PC then upgrading to Win 7 with out the CD?? 

 

Thanks Guys 

this might help

http://www.maximumpc.com/article/howtos/how_use_your_windows_7_upgrade_disk_fresh_pc