In evitably with any "homebrew" project like this Pentium 4 system in a shoebox, you need some strange parts. For the Mocha 620, here are some:
* LOGIC Supply Slimline CD to IDE adapter. This slimline CD to desktop IDE adapter is used for converting a laptop CD-ROM or DVD drive with a 50-pin connector to a desktop enhanced IDE (ATA) 40-pin connector. Power is supplied through a 3.5" 4 pin mini connector. Two analog audio connectors use the standard 4-pin connection. It is just $7, but pretty hard to put a notebook CD into a desktop case without it.
* "Notebook HD to IDE Converter":http://www.logicsupply.com/product_info.php/products_id/165. Others stock this, but it takes a Notebook 44-pin hard drive and converts it into a standard 40-pin IDE desktop adapter plus a Molex power connector used in desktops
* "USB front panel cable":http://www.logicsupply.com/product_info.php/cPath/24/products_id/170. If you are moron like me and have ripped out some of these tiny connectors, here is something that takes a USB header on a motherboard and connects it to another PC card.
* "Cooler Master Pentium 4 CPU Cooler DI-7H53D-08":http://www.logicsupply.com/product_info.php/products_id/279. A low profile cooler for Pentium 4 socket 478 systems. 31dBA and $18.