reads on an SSD are fast, writes are slow. don't do too many writes for too long. there is a limit before you start getting permanent bad blocks.
there is a wear leveling algorithm, but there still is a maximum number of writes per block with flash. that depends upon the technology and the model. SLC has 1x more writes but is usually 10x smaller, MLC is the lower of the two. then there's TLC. look them up on wikipedia. the samsung 840 pro ssd's are TLC. I try to use them either for speed testing or for read-only storage pretty much.
key point is, if you are going to have virtual memory which requires a lot of writes, put THAT on a different drive like a hard drive! that can reduce the lifespan of your SSD, but I don't know by how soon since I don't know what the number of writes are for VM - it varies from system to system because of RAM size, application memory usage, among other factors. get at LEAST 4GB of RAM and disable VM if you are getting an SSD would be my best advice. that way your SSD's only writes will be for application changes, updates, configuration changes and application and document saves and edits, service packs.
I have seen what an ssd can do on my system, as the boot drive. it sped up by about 3-5x. it was a very noticeable improvement.
but it was not a configuration I thought I could keep, since I figured that many of my applications would have to be installed on the windows drive due to installer limitations and auto-updates (not entirely sure about this, it depends on how the app's installer script was written).
just avoid incessant writes as a rule. you can track this using performance counters in perfmon. [windows-logo-flag-key]-R perfmon [Enter]