So whats the difference between R2 Standard and R2 Enterprise?

Standard i can get free with my microsoft dreamspark student account.
And Enterprise i need to use some "backdoor" ways to get my hands on it.

Also that tweak guide from here, that disable services.
Is it for the Standard or Enterprise or all of them?

Hi runeazn, if you haven't already discovered it for yourself there's a comparitor widget on Microsoft's site here (use the right panel to navigate options); but the Comparison By Technical Specification Grid is probably what you're looking for.

Service are pretty uniform across all editions of Server 2008 R2, some will have a few additional services to support specific features, but it's essentially the same OS regardless of edtion; so any tweaks you you choose will work regardless of edition...