Just be aware there is a huge difference between the $40 and the high end IDE RAID adapters. The entry level adapters use your processor to handle all the calculations needed to ensure proper handling of your data. So expect a major hit in CPU utilizaton. Most cards are based on the Highpoint 37x series or the Promise chipsets so there is not major differences between the various entry level models.
The higher end adapter like the 3Ware Escalades, Adaptec 2400A, and the Promise SuperTraks all use dedicated processors. Not sure what 3Ware uses by the latter use the same Intel i960 found on many SCSI RAID adapters (Many SCSI RAID Adapters now use 200Mhz ARM Processors). In addition, they usually have onboard memory to cache information waiting to be written to the drives. Some are expandable upto 256MB last time I checked by dropping a 168pin ECC SDRAM module onto the adapter.
Lately I've liked the Highpoint RocketRAID 404. Sure it a little more at around $80 but its a nice investment if you plan on moving on the RAID5. Plus it has 4 independant channels for performance reasons. It's still software RAID using your CPU but its a cut above.
Windogg