Minimising is a rather bad solution one very vital reason:

Lack of overview of your alts. Sure, you still have your main's UI, but it falls short in suprisingly many situations. You'll never be 100 % in control of your team.

If you have the cash, I do suggest, like Wilbur, that you get your hands a Quad-core or a strong dual core (make sure your wife gets you a good one for christmas :P). 5 clients is a pice of cake for my Q6600.

Also, you miiight wanna invest in another gig of memory, especially if you're running five accounts, but I'd recommend checking how you'll do with the dual/quad core first.