Recommend a cheap RAID controller...

I'm looking for the cheapest one that will serve well.

I found a Koutech for only $17 but it says it supports software RAID. What's the difference? Sorry, I'm a bit of a newbie here.

Promise Fasttrak100 TX2 gives you a good performance, without much $$. Its a very common Raid card maybe $20-$30

stay away from cheapo silicon-image-based RAID card (those ones you can get for less than $30 shipped online) .. I used one for RAID0, and it corrupt the drives once in a while ... switched to promise card and problems went away ever since.