Fenril, USB standard supports up to 6 keys + modifiers and has 2ms latency due to being based on polls while PS/2 support all keys at the same time and is interrupt based (no polling) - I still think the keyboard needs to support N-keys rollover as I dont think all ps/2 keyboards has that feature. But I could be wrong about that.

The one I gave the Lycosa to had it working just fine, but he is using Windows XP (I use Windows 7), so it seems very random if it works or not.
Aside from the serious ghosting issue and needing replugs randomly I loved it, as for the 5$ keyboard being better thats what I had to use until I got my current keyboard - I cant use a keyboard that dont work properly on my computer Its prolly a nice keyboard if you dont mind the ghosting and it works on your pc.