What hard drive enclosure do I need?

We just took apart our old Dell Inspirion 3000. Took out the hard drive and looks like it's an IDE. It says 40 GB, s/n X24C8386T
HDD2170 ZEO1
I want to turn it into an external harddrive but I can't find a good looking enclosure around 10$ or under (can't find the right specs)
it's 3.5 inch. from the port to top, and 2.5 inch. across

Sounds like a standard 2.5" laptop hard drive to me. You want enclosure that holds 2.5" and takes older style ATA not SATA. There's also USB dongle that plugs into hard drive without enclosure, and 2.5" won't need external power.

eBay seems to be the only cheap source but the quality is often questionable as well.