XP on iMac for Gaming

[nymets98]

I am going to partition my iMac (Early 2008) in order to install Windows so I can play Simcity 2013 on it (The mac version hasn't been released yet). I have an extra copy of Windows XP that I am not using. According to the system requirements, the game will run on Windows XP. I do not know if it is worth it to purchase the $90 upgrade to Windows 7 just for the few months or so I will actually need Windows to play the game. I guess my question is, will their be a significant performance drop if I play the game on XP instead of Windows 7, and if so will the performance on XP be very bad. When I say performance I mean overall smoothness of the game.