Well, the only difference is the desktop's processor (Intel Core 2 Duo 1.82 GHz, 4 GB RAM) is a bit slower than my laptop (Intel Core 2 Duo 2.00 GHz, 4 GB RAM, T6400), and of course, the desktop has a graphics card and sound card installed in it (which I thought would help). Both of them are running Windows 7 the only thing is, my laptop is a 64-bit and the desktop is 32-bit. Other than that, everything is the same. I just have different antivirus programs running on them. The laptop is basically a backup copy of my desktop.
The desktop runs MC fine in single player, so I'm hoping there is something I can tweak to make it run better in multiplayer. I might need to check for updates for Java, but thats the only thing I can think of. MC is also using an fuckton of resources (over 500,000 K). Does it really have to take up so much?