I would like to replace the Optical drive in my computer with a SSD drive. My computer only has room for 2 HDD's. Since I rarely use my optical (dvd/cd) drive, I would like to swap it out with a 128GB vertex 4 and use it as my boot drive. Would this work OK?
Yes you can, assumigh the dvd drive is a sata attachment.
A SSD is very small, and can fit most anywhere.
If you have an extra sata port, and a sata power connector, I would try to add the ssd.
You can even use duct tape to keep it positioned somewhere inside of the case.
One good use of a dvd drive is for recovery. If you ever need to reload windows or do a repair operation, it is nice to have a bootable dvd available.