For most people, software RAID (motherboard based) is fine, and matches or beats some add-in cards in regards to performance.
Why RAID SSD's... in my case I hate waiting for programs to open. 14-18 seconds for Photoshop / Premier Pro to open on a single SATA III HDD, wtf... Using motherboard based RAID-0 & a pair of SATA III 120GB SSD's Photoshop & Premiere Pro now opens in about 2 seconds. BTW, I've seen results for $500 - $600 add-in hardware based RAID controllers on these same SSD's, the extra 2 - 4% read/write speed increase, not worth the cost IMO. Of course, different motherboards may show different levels of performance based on BIOS, RAID controller, & drivers.
Boot times are also noticeably faster on my system under RAID-0 on those SSD's, 12-14 seconds faster in Win 7 Pro, 22-26 seconds faster in Win 8 consumer preview (not current "Release Preview"), that's after adding the delay from the RAID controller having to initiallize before Windows can start up.
If you can swing it. you might consider a 256GB OCZ Vertex 4 SSD (currently $210 at newegg before M.I.R.), for your primary drive. Then use your current SSD, as Airheadq suggested, to create a hybrid drive with your HDD for improved throughput there, & enjoy the best of both worlds... BTW & FYI, a single Vertex 4 256GB SSD has better read/write performance (in AS-SSD & Crystal Disk Mark) than my RAID-0 SSD's (2x Mushkin Chronos 120GB SATA III) by about 10% - 15%