You should NEVER RAID-0 a HDD and a SSD.
The performance of a RAID-0 array is based upon the drive in the array with the slowest Read/Write speeds, which in this case would be your HDD. If your HDD has 100MB/s Read/Write speed, then in RAID-0 with a SSD you will get a maximum of 200MB/s, which is a waste of your SSD's capabilities.
The total capacity of a RAID-0 array is based upon the drive with the smallest capacity.
So if you RAID a 80GB drive and a 2TB drive your total capacity will be 160GB (80GB x 2), not 2.08TB.
For maximum performance you should use identical drives when creating a RAID array.
Just use the SSD as your O/S drive and the HDD as your data/storage/backup drive.
ok, so should i use an AHCI controller, or 2 raid ready arrays :P