If you have one harddrive in your system, the C drive is your primary drive and the D drive is a partition off of your C Drive (assuming the D drive is not your CD/DVD rom drive).
This D drive is possibly reserved for System Recovery Console Files which bring your system back from the dead when things go terribly wrong.
-I don't recomment tampering with files in your D drive.
Your options are:
-If your data on the C drive is important to you, you could back it up by mooving it to CDs or DVDs
-You can try solid state containers such as USB flash drives. ($10 for a 4GB; $20 for a 8GB; $40-$60 for a 16GB and $100 for a 32 GB on newegg.com Computer Hardware> Flash Memory & Readers> USB Flash Drives- if you're interested)
You can Purchase an external Hard Drive which would be a bit more expensive but you can have 500GB of storage for about $80. Again, on newegg.com.
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-If your data is not important to you, you can just delete some of it by uninstalling some unused applications/software and manually removing documents from the C drive and the Recycling Bin.
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--To squeze the last bit of space from your Hard Drive you can:
-Run Disk Cleanup and delete all temporary windows files allong with everything else you can find the except for "Compress old Files" (do not recommend)
-Clear your Browser Cache/History/Cookies
-Empty the Recycling Bin
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The bottom line is, there's not much you can do about getting space from your HDD without deleting stuff. And doing Disk Cleanup and the rest of the stuff below it will not do any good for you in the long run.
Your best bet is to just invest in a nice, mobile, spacious external Hard Drive.
External Drives Page
They also have them in a very small (physical) size that run off the USB port power and do not need to be plugged into the wall.
320GB USB External from WD (this is the "no power cord" one)
Hope this helps.
(sorry about me always directing you to newegg, I love them, they saved my life a 100 times)
