A RAID 0 will likely give you the most performance from your disk drives without stepping up to faster RPM drives or SAS drives. Adding another 160gb in a RAID 0 will also double your storage. If your on top of your backups, the original 160 isn't to old that you think it might be at the end of it's life I'd say go with another 160 and set up a RAID 0. Make sure your mobo will allow you to boot from a RAID and support RAID 0 before you do it though.
but for more info: i bought my current harddrive in April 2007 so, it has been used for a pretty long period but does not have any issues and no sounds if working intensively. so shall i still go for RAID 0 ?
should have given this info in the first post Sorry !!!
It's under a year old I think you should be fine. When I think of "old" drives i'm thinking more in the 3-5 year range. I'd still run the RAID 0 unless your getting cold feet about data loss. RAID 0 is always a gamble for performance over reliability. However if you only have one drive you run the same risk but without the performance. Go for it!