Check out the following threads about renting:
http://www.clubsnap.com/forums/showthread.php?t=348675
http://www.clubsnap.com/forums/showthread.php?t=345104
http://www.clubsnap.com/forums/showthread.php?t=359995
thanks alot! maybe i shld rent the EF-S 17-55mm f/2.8 IS USM first. hahah