The latest Intel Rapid Storage Technology driver is here:
Intel Rapid....
They renamed the IMSM to IRST. It's a self installing application (once downloaded and ran), updating the chipset drivers for your Intel based (X58 or P55) motherboard.
Like vvhocare5 said, the individual driver aren't displayed in Device Manager when they are part of a RAID array. It's given a name, which yours is "Gen disk RAID 0," but I could name mine "Intel RAID0" and "Seagate RAID0," or something like that.
For further info, try this:
The SSD Review. But be warned, I did this "tweaks" and then screwed up my OS so bad, I had to reinstall Win7, and then left everything alone! I did move my pagefile.sys to my HDD, but I have 6GB of RAM, so it's never used. All my data/media is on the HDD array. And I back up frequently (weekly)!
And since you have 160GB of SSD space, I wouldn't worry about the "saving drive space" tweaks, except disabling Hibernate. Hibernate and SSD don't work good together.
Now you know, that since you have your SSD in a RAID array, that TRIM is unsupported? It may say that it's enabled, but it's still (currently) not doing anything. Then again, you have plenty of space for the drives, just don't go over 80% of usage (128GB). Even my setup is unsupported, but I haven't noticed any degredation. Sometimes it's a little slower, but then recovers.