Here's two ways you can get back some of your lost hard drive space. I did this and got (if I remember correctly) around 4-5GB back.
Recycle Bin
1. Right click on your Recycle Bin, and click Properties.
2. Where it says "Maximum size of Recycle Bin (percent of each drive)" with a slider over that, drag that slider to something like 1% or 2%. This essentially makes your Recycle Bin smaller, so it can't hold as much.
After you lower the percentage from 10% (I think that's the default) to say 2%, that means your Recycle bin will use up 8% less off your hard drive, meaning that space is now yours to use in other ways. My Recycle Bin is set at 1% because either way, when I send something there I'm going to delete it, so what difference does it make how much it holds?
System Restore
System Restore is a way for your computer to go back to a previous state in case of a failure
- . Your system (I know this is on Windows XP, I don't know about other OS's) automatically creates restore points for your computer. But you probably don't need so many of them, unless you plan on going back to a point several weeks in the past. System Restore points take up a lot of space on your hard drive. Here's how to get that space back:
1. Right click My Computer, and click Properties.
2. Select the System Restore tab.
3. Under Disk Space Usage, there is another slider which I believe is at 10%. Drag it down to 2-4%. Mine is at 2% (637MB).
I checked how many restore points I have [Start>All Programs>Accessories>System Tools>System Restore>Restore to a previous point] and I have around 12 in this month alone. That's way more than enough for me. Again, I got back around 2GB of space on my hard drive.
And that's all there is to it.