Get a "Fast Ethernet" card for your desktop. Gigabit PCI NIC's are cheap these days.
Make sure the patch cord/crossover cables are wired correctly (if you made them yourself).
Then share the desktop internet with the laptop (if you can get ICS to work) or get a router to share source internet.
If you have a fast Ethernet card already, check it's properties and make sure it's speed is not stuck on 10mbps.
so instead of hitching my desktop to get internet through my laptop just get a wireless card ?
I'm missing something here on your configuration. A router is your best option. Connect internet to router to distribute internet to each computer for the least hassles. Routers are cheap and are made to do what you are trying to do. If you go with Internet Connection sharing, both computers must be on at all times to make things work... why be saddled with that?