Do not over-upgrade a 386 or a 486. A better investment would be in newer technology such as a Pentium class machine. If necessary, cut back on groceries or lotto tickets for a few weeks. Get the system up to at least four MEGs. RAM can be bought from a company which advertises in a computer magazine or a good local computer retailer.
RAM speed is measured in nanoseconds.
Most RAM is 70 nanoseconds. Everyone seems to have a computer-whiz friend who would just love to help out. This route may save a little money, but be careful. Some people only talk a good game. Having the job done at a computer store may save you money in the long run.