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.
The H200 can present at most 2 logical drives (virtual disks) so your plan for 3 RAID groups wont fly with the H200 controller alone. You could configure the SSD's in one RAID 10 group, and the 8 SAS HDD's in the other but that wont deliver isolation between the IO on the two data drives.
Which document are you referring to that states that the SAS drives must be in slots 0 and 1 for mixed SAS\SSD setups? The H200 user guide doesn't mention that restriction, the only restrictions that are mentioned are that all drives in a RAID group must be either all SSDs or HDDs and either all SAS or all SATA.
Best Answer
A good primer for SSDs is to read this anandtech article.
For regular desktop use (gaming, office, productivity, what have you) SSD will kick 15krpm SAS drives around easily, since there's a lot of random reads and writes involved. You do have to be careful in choosing the correct SSD though, choosing one of the older models won't give you that much of a performance difference.
If, on the other hand, you're doing a lot of sequential read/write, like for instance editing videos and working with large data sets (moving large VM images around, etc), the SAS drives will be very fast. On the other hand, the SAS drives are just as fast at it as fast SATA 7200rpm drives.
So, it all depends on what your use case is. If you're planning for normal desktop use, SSD is the way to go. For big chunks of sequential r/w you'll be better off with a pair of spinning drives.