SSD for system and HDD for data for Desktop environnement

This is mostly an educated guess, as I have not tested such a configuration.

I would say using a small, fast hard drive for the OS and programs would be a good idea. This does not have to be an SSD by any means. It could help if you need to be stingy on power, but would cost much more, and have less capacity, than using a 100GB standard HD. As another answer says, Vista and developer tools would likely not fit in 32GB unless you were very careful which components from each are installed. Even then, maybe not.

My recommendation would be to save the money and get a 80-120GB main drive that is fast, then a larger, slower drive for data. If you decide to go cheap on the second, slower drive, be sure to run backups on the data periodically. A 10k or 15k spindle speed drive is generally not a great idea in a desktop workstation, as it adds heat, power draw, and vibration to the system for very little real-world performance gain, in most cases.

As for what to watch out for if you decide to go SSD, watch for manufacturer and read the warranty terms. Also, look at real-world benchmarks, as some SSDs have been found to be unbearably slow.

32GB for a system drive is getting tight these days, especially for those who run dev tools that can easily eat 10+GB themselves. I've not done this exact setup (yet, a new system like this is on order), but my current Windows machine has a 30GB WD Raptor for OS and a 1TB Seagate for data and it's amazing how much faster even the Raptor is.

In Windows having most programs installed anywhere other then the default location (%PROGRAMFILES%) is a pain as some stuff does break. Also, if you're not going to use the SSD why bother buying it, you only boot once a day.

In terms of SSD's there's really only two MLC (ie, cheap-er) options that are any good. The best is the Intel X25-M, but it's expensive and the number two is the OCZ Vertex, the 30GB version actually being cheaper then the smallest Raptors here in Australia. These SSD's can be simply treated like small fast hard drives, and need no special treatment.

Almost every other SSD currently out there is either garbage, or really expensive.