Which Version of Windows 7 Should I use?

I hve a fairly new Macbook Pro. Mid 2012 Version just before the new display came out. My question is, which version of Windows 7 should I use? I've noticed that I can purchase either the 32Bit or 64Bit version, but I am not sure and don't want to load something that might be bigger than I need. I'll only be using Windows to run The Sims 3. This means over 9 expansion packs+ and their EA store content.

Here is what I am running on my mac:

Model Name: MacBook Pro

Model Identifier: MacBookPro9,2

Processor Name: Intel Core i5

Processor Speed: 2.5 GHz

Number of Processors: 1

Total Number of Cores: 2

L2 Cache (per Core): 256 KB

L3 Cache: 3 MB

Memory: 4 GB

Boot ROM Version: MBP91.00D3.B08

SMC Version (system): 2.2f38

Serial Number (system): C1MHN1TNDTY3

Hardware UUID: 8CCE66F6-C4B6-5EDB-9CE7-FFB43E25F89D

Sudden Motion Sensor:

State: Enabled

As you can tell this isn't a higher end Macbook Pro, as it was a gift, but I am unable to play the game without it crashing since they do not have an updated patch for Mac users - and it is very unlikely that they will even care to update the patch. This seems to be the only guarenteed fix. I appreciate any help I can get, I just need responses soon so I can take advantage of the low prices for Windows 7 before they run out.