Make sure it has a dual core processor. I would suggest a laptop so that you can work on the same projects anywhere you go. A centrino duo or core 2 duo with 2 gigs of ram would be ideal for 2 dimensional drafting software. Oh and of course a cd burner. Those are necessary, everything else is up to your needs. I would not suggest MS office as it is a rip off.
www.openoffice.org - Free office software - Word processor, Speedsheat, presentation software, etc. etc.
Ideal specs for a engineering student:
.Centrino Duo/ Core 2 duo
.2 gb of ram for multi tasking as well as 3d drafting software
.100 gig hd should be sufficient if you plan on running crap, WHOOPS i mean Windows.
.A good video card ATLEAST 256 mb of vram (intel x3100, Ati Radeon, Nvidia GeForce) - try to get a card with installed vram as opposed to onboard memory which shares memory with your system ram and runs A LOT SLOWER.
A cd/dvd burner to burn backups of projects and other data will come in very useful.
.Windows XP - Personally, I use linux but for AutoCAD you will need windows - STAY AWAY FROM WINDOWS VISTA it eats resources and will slow down your pc dramatically.
I would recommend a laptop - HP dv2005T or Sony FZ140E. Both Great for engineering students both new with the latest technology.
If you plan on getting personal copies of AutoCAD and MATLAB be prepapred to pay top dollar if you plan on purchasing them legally. You can always download them via torrent software - But that is illegally pirating software if you don't mind doing that as most college students don't - by all means. Otherwise, be prepared to pay $1500 for AutoCAD