RAID 0+1 refers to a separate RAID level, where both striping and mirroring is involved. You need 4 disks to do this.
What you mean is the MatrixRAID feature; essentially you have both a RAID1 and a RAID0; like when using software RAID on partitions. You have one partition that is RAID1 and the other partition is RAID0; so with 2 disks you can have both the security of mirroring and the performance of striping, but only one of the advantages on a partition.
So to make it simple, your RAID drive would look like:
C: <RAID1 for security>
D: <RAID0 for performance>
You can also do it the other way around, but that would mean that if one drive fails you cannot boot Windows anymore. So carefully weigh the advantages of the two approaches.
What to put on RAID1? Well for example your operating system, but also your personal documents you want to keep safe, such as personal photos and text documents.
The data on RAID0 would be replaceable data, such as downloaded stuff you can re-download if its lost. But you cannot re-download your personal photos those are gone if your disk fails, without RAID1.
I do want to warn though, that using RAID1 or mirroring can never fully replace a backup; a backup prevents against much more dangers than just a drive failure. Also, RAIDs can fail even with the disks themselves being perfectly fine, so the RAID layer adds a certain risk of its own. Please do backup the most important stuff you just cannot afford to lose. You can do this with an USB stick, external drive or simply store it on another computer on the network. The amount of 'critical' data is usually quite small for most people.
To setup MatrixRAID, connect the disks to your motherboard chipset SATA ports, go into your BIOS and enable RAID mode, then reboot and it would prompt you to press Control+I or some other combination of keys, to enter the MatrixRAID setup. There you can set up your disks the way you want, and afterwards install Windows.
Installing Windows 7 is the most easy, as it appears to have drivers for the RAID already integrated, but other Windows releases require you to press F6 and insert a floppy/USB/CD with the RAID drivers, to allow Windows to be installed on the RAID.