If your equipment supports it; x64 is really the way to go (improved compilation time, a much higher maximum drum). RAM is terribly cheap these days, and if you finish working with Windows7 in a few years; it is very likely that you will like 8 + gigabytes of RAM.
I could not find Windows 7 32 bit versus 64 bit test, but here is one of them for Vista.
http://64-bit-computers.com/windows-vista-32-bit-vs-64-bit-benchmark.html
The 64-bit version is superior to the 32-bit OS.
In addition, the differences are quite superficial for your needs. At least from what you posted. Look below and see what something should be. Each progressive version includes all the features of the earlier ones - if you really want Windows 7 to encrypt the file system - you can go with a professional or something higher.
The following is a brief description ...
Windows 7 Home Premium
- Aero Glass and the advanced navigation system Window
- Windows Touch (Multi-touch and handwriting support) Video demo, Learn more here
- Windows Media Center
- Internet Explorer 8: Web Slices, Accelerators, InPrivate Browsing
Windows 7 Professional
- Domain Registration (Walkthrough)
- Group Policy Controls (more)
- Location Aware Printing
- Encrypted file system
- Advanced backup (first look)
- Offline folders (more)
- transparent caching, background synchronization for offline files
- Remote Desktop (more)
- Windows Mobility Center: Presentation Mode
Windows 7 Enterprise
- DirectAccess supports connecting mobile users on the go.
- BranchCache Speeds File Access (TechNet Description)
- Search for information on PC, mail or SharePoint
- BitLocker protects data on PCs and portable devices
- AppLocker lets you control which users can run
- Virtual Desktop Infrastructure Improved
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