Should be fine, no issue.
Whether it will be slower or not depends where you have the OS
It is Possible,
Just Buy SATA BACK PLANE with 3 Hard Disk Options ,
Intel Too Manufatures it, Part Number :AXX6DRV3GEXP
Then Insert Your 160 HDD as Primary and the 1 TB HDD as Secondary, Then It is possible to use it.
If you use to RAID FUNCTION it wont work , Unless two HARD DISKS ate of SAME MEMORY CAPACITY with The Efficient RAID CARD.