Solid State Drive's if you have not already purchased one for your C drive do so whenever you can the difference is amazing. my C drive is using 83g running w7 home premium 64 bit with the SSD my system is rated 7.7 of 7.9 without it the rating was 5.5 Yes I know the rating is stupid but at least you can compare apples to apples with it
I could even tell you how to clone your C drive so that you can perform the rocket surgery in about an hour
The difference in system and program startup time is amazing and worth the price alone. I'm in Adobe CS most of the day and I couldn't imagine life without SSD now. E.G. on my old computer Photoshop would take a lifetime to startup. Now it's literally open and ready to go in 5 seconds.
OS on the SSD and Data on a 10,000 RPM HDD. Runs like a dream. Boots up in about 8 seconds from cold start. SSD for the win.