Bear in mind that this system can run at 6 GB/s and the v4 can only run at 3 GB/s thus a m4 would be better.
This system has a mSATA port which is probably unoccupied. Also in my opinion 32 GB is too little too small to install a Windows 7 OS, I just managed to install the OS and Office on a 64 GB one (my documents and files are elsewhere) and this is a push for space; if you can afford I would recommend the 128 GB mSATA m4 SSD: http://www.crucial.com/uk/store/mpartspecs.aspx?mtbpoid=050B0AA0A5CA7304
Such a small drive may work as a Cache Drive but this is more bother than its worth to set up.
For other upgrades see: http://www.crucial.com/uk/upgrade/Dell-memory/XPS/XPS+8500-upgrades.html
I've just ordered an XPS 8500 with 2TB HDD and 32gb mSATA (got a decent deal in the DELL January sale ;-) . Given the mSATA supplied will be configured out of the box for Intel SRT caching, I am considering moving the system partition to SSD by either:
A) Adding an additional 128GB 2.5" SATA Rev3(6/GBs) SSD to slot 0 for the system partition and recover Win8 but continue to use SRT caching on mSATA as-is with existing 32 GB. This option would see existing HDD moved to a SATA Rev2(3GB/s port). or
B) upgrade existing mSATA to 128GB and reinstall Win 8 as system partition on mSATA leaving existing HDD as-is.
I believe that having a 6GB SATA SDD for the system partition should significantly boost performance right?
Cheers for any advice.