Can I make an INTERNAL hard drive EXTERNAL?

I have been wanting to get an external hard drive to back up data for both my desktop and my wife's laptop, but they're just so doggone expensive. A friend told me that I can buy an internal hard drive with some sort of a case, get a PCI card with an external SATA hookup, and I'm good. I figure this would be cheaper (and a smaller profile to boot). I've already got Acronis True Image so I don't need any backup software. What do I need to look for when I'm shopping for stuff? I'm looking for at least 300 GB

Yeah just buy an external HD enclosure and bingo instant portable HD. Most of them use PATA IDE HDs and USB to connect to a PC.

Ones like these perhaps:

http://www.newegg.com/Product/Product.asp?Item=N82E16817146174

http://www.newegg.com/Product/Product.asp?Item=N82E16817173008

http://www.newegg.com/Product/Product.asp?Item=N82E16817186102

two of the three you recommended only support IDE drives, and one seems to be designed for CD/DVD writers. I'm looking specifically for an external enclosure for a SATA drive.

does it really matter just about made in china
look here this should do it sata enclosure (http://cgi.ebay.com/USB-2-0-External-Case-for-3-5-SATA-IDE-Hard-Drive-B21_W0QQitemZ8739335089QQcategoryZ116257QQrdZ1QQcmdZViewItem)

Oh, SATA huh, I found those links with a quick search. Another quick search found ones like these:

http://www.newegg.com/Product/Product.asp?Item=N82E16817146318

http://www.newegg.com/Product/Product.asp?Item=N82E16817123124

http://www.newegg.com/Product/Product.asp?Item=N82E16817155223

http://www.newegg.com/Product/Product.asp?Item=N82E16817145163

absolutely. I'm using one now. You have to by a USB to IDE converter. You can get them for about $20 on ebay brand new. They come with a power adapter and a USB cable that ends in a IDE connector. Most good kits also come with a 3.5 inch converter.

You can fabricate a container from some wood.
I simply use the device as an ultra large USB drive to transfer files from computer to computer.

oops - you were looking for SATA.... I'm sure they have them also.