To add to the already muddled SSD discussion, I would advise against any of those SSD's.
OCZ has developed a bit of a bad rep as of late, both for reliability and for customer service, so while the vertex 4 may be faster than other ssd's, I consider it a bad risk.
As far as the rest of the SSD's suggested, they all use synchronous NAND as far as I can tell. The type of NAND used affects SSD speed more than any other factor, and toggle NAND is currently the fastest. I would suggest one of those.http://www.tomshardware.com/reviews/ssd-review-benchmark,3139-6.html
the 256gb crucial and 250gb intel are in the same tier as 120gb toggle NAND, sandforce ssd's. that indicates that a toggle nand sandforce based ssd is approximately twice as fast as a synchronous NAND, non sandforce ssd.
To add to that list, the sandisk extreme also uses toggle NAND and a sandforce controller. Any toggle NAND sandforce controller SSD will give you practically the same performance, so it comes down to price and reliability. Intel does not yet make a toggle NAND ssd, so I recommend the sandisk as both the cheapest 120gb, and possibly the most reliable as well (it's only been out for a few months). Sandisk not only makes their own flash memory, but has also been making enterprise level ssd's for almost a decade.