should I close old unused credit cards?

[basco]

Quick primer: I'm 22, have been working at a real post-college job for the last year, and only use one credit card. In my innocent (read: foolish) youth, I was swindled into signing up for various credit cards for free shirts, towels, or whatever. I just got my free credit report and sure enough, in addition to the one credit card I actually use (a Target card with a $2500 limit) I have three other lines of credit that I have never touched, and several charge accounts that I signed up for in store once and then never used again.

Credit cards
Target NB: $2500, opened 2005, primary card
American Express: $600, openend 2001, never used
University of Wisconsin: $500, opened 2001, never used
MBNA America: $1000, opened 2002, never used

charge accounts
Kohls/Chase: $1000, used once
Marshall Fields: $1500, account, used once

closed:
Bank of America
RNB-Fields3

The thing is, I think these accounts are actually helping my credit score - they're accounts in good standing with no late payments, and they've been around since 2001 or so. I only use the target card with the $2500 limit, however lately I'm spending about $2000 over a 2 month period, (and that's too close to my limit, right?) Should I apply for an extension for my Target card and just leave these old accounts? Should I get apply for a card from a real bank? Do I close these old accounts? Do the charge accounts have any bearing on any of this? Don't feel like you have to answer these questions, I'm just giving you an idea of how confused I am about this. [img]/images/graemlins/confused.gif[/img]

Any advice is greatly appreciated.