Here's my setup:
- 128GB Samsung Series 830 (more reliable than those Sandforce controllers; if you do go Sandforce, though, make sure the FIRST thing you do is update the firmware). On this drive I have MS Office 2010 (wtf is wrong with Office on an SSD?), Win7 Pro x64, Adobe Photoshop Elements, Adobe Premiere Elements, BF3 and pretty much every single program I run that isn't a game (aside from BF3, obviously).
- 1 500GB HDD that contains all my Steam games and a few installation files.
- 1 1TB HDD that contains all of the data that would otherwise be located in my Libraries on the C: drive. Just a right-click and reassign the Library shortcuts to the appropriate folders on my 1TB and I'm good to go. I used to have everything running off the 1TB, but after I divided everything up, I gained a lot of space.
When buying an SSD, buy as much as you can afford. I would say 120-128GB is the absolute minimum, though. After formatting, my 128 is only a 119GB and I have 50.2GB free at this point. Aside from Steam, though, I run all my programs off the SSD. That's the point of an SSD in making the entire system faster - there's no point in putting just your OS on the SSD because at the end of the day the price difference between a 64 and a 128 isn't that huge at all when you look at the STARTING price of the 64GB.
Besides, when you buy starting at 128GB, you often get a few extra features in the hardware that you otherwise don't get. There are a few special features that Samsung listed as not being available on the smaller Series 830 drive, plus it was too small.
I would also recommend you to get Samsung on the following points: you can update the firmware within Windows, no need to boot from Linux or wipe your data every time there's a firmware update. Just run Samsung's software suite and you're done. Samsung provides you with Norton Ghost software to backup your discs. Samsung also designs its controllers in-house and doesn't rely on a third-party like a lot of the other manufacturers do meaning that if there is a problem with the firmware, it gets fixed a lot faster than it otherwise might. This is exactly the reason why Sandforce controller drives like the OCZ Vertex that everyone is recommending to you above had to live as long as they did with such shitty reliability. Sure the drives were lightning fast because the software makes the most difference with SSDs (algorithms and whatnot), but the OEMs only sold you a drive that had a system critical component that they had absolutely ZERO control over.
