For engineering and design work an Intel Pentium processor is a must. Buy enough memory. Some engineering software may require more memory, but in general the requirements of business accounting software are lower than the requirements for entertainment software. New software programs offer many features and require large hard disk storage. It is wise to invest in a large hard disk drive and a 540 MB hard disk is the minimum you should consider today.
Output is important.
If you will be doing mostly design work on the computer, a larger size monitor may be desirable. You should insist on a Non-Interlaced type of monitor, for less flicker and reduced eyestrain. Colour inkjet printers are very popular with home businesses since they generate high quality printouts, they can handle letterhead and envelopes conveniently, their prices are reasonable, and they are reliable. Expandability is a plus. Make sure the computer has a drive bay to add a CD ROM drive or a tape backup unit, and it has free expansion slots to add a fax modem, sound card, and other expansion cards.