What you're proposing is an ideal configuration for speed and data redundancy. Your OS/programs will run fast off the SSD, and your data can be accessed off the HDDs. The RAID-1 gives you redundancy against a single HDD failure.
One thing you need to be cautious of is ensuring you have adequate free space on your SSD, since SSD controllers have TRIM/GC functionality that uses that free space to keep SSDs performing well.
The reason I flag this up is that a new install of Windows 7 will take up a modest amount of space, but over time, Windows Update will eat up space.
I'd recommend you keep the SSD filled up with a newly installed OS and programs upto about 40-60 GB, so over time it can grow, without reducing free space to the extent that SSD housekeeping is affected.