If you are going to use it as the system driver your windows and all programs are going to load a lot faster. It is very useful in everyday work. If you have the money go with Samsung 830 or 840 128GB.
SSD won't help with games much, they will load a little faster but won't play faster. For everyday PC work, surfing websites, office tasks, etc, it will be so much faster. If all you care about is games don't worry about getting a SSD
1) I strongly recommend a 120GB SSD. Yes, it will add about $100 to the price, however, it not only adds performance to Windows but allows you to create a periodic BACKUP IMAGE of your SSD to the hard drive in case of any problems (virus, main drive failure, software glitch). It happens quite a lot.
SSD-> Windows and programs
Hard Drive->SSD Image Backups, Downloads, STEAM Game Folder, media
- Samsung 840 Pro (if you want the Assassin's Creed 3 coupon; I just bought this in Canada for $143)
- Intel 330 or 520 (520 only if not much more than the 330)
- OCZ Vertex 4
*There are a few others of similar reliability. Note that the "Samsung 840" (non-Pro) uses "TLC" NAND which isn't as reliable as the MLC of the Pro version. It's just too new to recommend.
**Regardless of SSD, make sure to flash it do the latest FIRMWARE before using.