Most laptop cooling fans that I've seen are a set size with a universal connector, but I've never taken a Vaio apart, so I can't say for sure. Best bet would be to find a laptop / notebook forum and post up there and ask. You could also try contacting Sony, but they would likely tell you not to take it apart, or try to sell you some crazy-expensive "sony brand" fan, that you might not need.
I'm spoiled - I found this right after I got my Powerbook:
http://www.ifixit.com/Guide/Mac/Powe...c-Board/63/16/
- Justin