Additionally the performance increase is important, but doesn't matter for everything network related.
In other words I'd say it's almost worth what you pay for it.
It's easily the most noticeable upgrade I've ever done.
But you can always have more than 1 hard drive. Buy a 500gig one for all your large file content and use the smaller one for the OS. Pretty much all SSDs come in laptop drive format so I don't know where this $800 number is coming from. They might have been $800 last year, but transistor prices drop pretty fast.
I have 2 drives in my macbook pro -- 120gig vertex 2 ssd, and a 500gig samsung "old style" hard drive.
The only real problem with that solution is that 128gb isn't enough for some people, but it is not difficult to offload the data to another storage device, either internally or externally. I've been keeping under 128gb on my main laptops (MacBook Pro and Air) for a year and a half now (when I first switched over to using SSDs) without a problem.
If you buy a sony or apple laptop, replace the drive yourself. I just bought a 13" MBP and bought a $25 caddy to put my Vertex 2 in the DVD bay. That way I have Windows 7 booting from that SSD, OSX on the normal HDD with extra storage available there. Of course you could just replace the HDD with an SSD and not void your warranty.