Well, the card reader type doesn't matter at all, as its just an passive element without any electronics. Fake features like "supports booting" or "DMA capable" can be ignored as the Adapter only converts IDE to CF connector. Important is to buy an "angled" version. There are versions where a plug is in line with the reader. These versions are also known as "direct plug", "vertical version" or "main board plug version". Don't buy those, as you will loose the opportunity to connect a secondary IDE device like a CDROM. Angled versions have the same connector as used on hard drives.

http://www.geit.de/tmp/cf2ide_1.jpg
http://www.geit.de/tmp/cf2ide_2.jpg

The compact flash card is just no name card. Just make sure you get a version supporting DMA. The faster the better, but even the slowest will increase your system speed massive.

Just pick the best combination of price and size that fits your needs.

Geit