That will work great and actually that's my recommended setup.
If those 300-gig SATA drives are old, I would not trust that storage with data you don't want to lose. Keep that on the SSD.
Alternatively, you can set the 300GB drives in Raid-1. Your write performance will be like a single drive, but your read performance will be like a Raid-0.
The setup steps are easy. Enter your BIOS and make sure you have your SATA controller set to RAID, and not IDE or AHCI. Once you have set that option, during your boot process you should see a RAID controller initialize. This might happen before or after your normal BIOS screen. On my system, I have two RAID controllers. I get a brief flash of the BIOS screen, then one RAID controller (the SAS RAID), then the second RAID controller (SATA RAID), then the BIOS does the rest of its thing, then Windows boots.
When the RAID controller initializes, whether before or after the BIOS, it should show instructions for what key combo to press to enter its setup. For me, the key combo for the LSI SAS RAID is Ctrl-C. The key combo for the Intel SATA RAID is Ctrl-M. I've seen all kinds of different key combos here, from F1 to Ctrl-A, all over the board. Just have to watch the screen. It's easier to do this before you've installed Windows, or if you have installed Windows, with the SSD disconnected. That way if you miss the prompt for the key combo you don't have to wait for the OS to load and then shut down and reboot, you can just hit the reset button. Also you know for sure you won't accidentally add your OS drive to the raid array, because it's not there to add.
Once you are in the setup page for the RAID controller it should be pretty easy. You'll have to follow the on-screen instructions and figure out the interface yourself because it's different for every raid card. Consumer RAID controllers tend to have a nicer interface. My SAS and SATA raid are built into a server board, and are quite difficult to navigate, but my other cards have been very easy.
Usually you select the drives first then choose to create a RAID on them. I think that's because your choices in RAID level depend on the number of drives you pick. Just select the two 300GB drives and your only options will be raid-1 or raid-0.
I recommend RAID-1 unless you really need the extra space. Your reads will be faster than normal and your writes will be as fast as normal, and if a drive decides to go out you don't lose data.