I've been using a Sandisk 32 GB SSD on a Dell Latitude D630 running Vista for about 3 months now. This wasn't cheap, and even with an early adopter mindset, this is a big disappointment; it does indeed reads much faster (about 30 times), but writes at least 3 times slower than the same D630 running a SATA. My typical usage involved web/email, Microsoft Office, photography/photoshop, compiling large projects, etc.
Quiet is great, more battery is fine, and I hardly ever reboot using Vista almost instant-sleep feature, but installing software or writing large files is *painful*. Moreover, you should plan for a lot of physical memory: you do *not* want to see your system paging for virtual memory.
Now maybe Vista is to blame, but the whole system will hang now and then for 10 secs or more. Is it indexing something, writing whatever system logs to disk, who knows, but a a few other users have reported the same issue with this SSD on Dell forums. No driver update has been released either since the SSD option was out. This is also probably not coincidental that SSD vendors emphasize read speed but remain somehow quiet about the write speed (or lack thereof).
I, for one, am switching back to a 7200 RPM SATA. This is *not* ready for prime time, even if Samsung claims slightly better write speed on its 64 GB; *do* check the user forums (say, Dell), and you will find a lot of frustrated users. This was worth a shot, and I'll eventually consider that technology again in 10 months.
Hope this helps