Appropriate partition size for Windows 7

I'm new to using a mac so I'm sorry if this question has been asked before. But i recently bought a late 2011 15" macbook pro with 4GB memory and 500GB 5400-rpm hard drive. I want to install Windows 7 64 bit through bootcamp but I'm not sure what's an appropriate partition size.

Now, the only reason I will be using Windows is to play League of Legends as it's not supported by Mac, that being said I'm not sure if that should be taken into consideration when deciding the partition size?

Thank you for your time!

Windows 7 x 64 bit needs at least 15 to 20 GB just for the OS and included apps plus IE. It really depends on how much you plan on installing to Windows 7 in the way of games and apps. I'd probably make the partition 100 GB which should allow plenty of room for expansion later on. Remember, Windows always creates a fairly hefty swap file which takes up considerable space.

i used VmWare fushion and believe it set automatically for 1Gb and 40Gb. i found out the hard way with vmware that i can increase my memory but cant decrease it. so if i add another 50 or so gb i cant downsize it. but yeah even 20gb would be a good start.