[New Computer - Very Slow SL - Any thoughts?]

It might be the Catalyst Control Center, which is the application controlling the video driver.  I had the same problem until I used CCC and reset it back to default settings for each option.  Then it worked great.

[How do I find places to buy clothes?]

Use the Search button at the bottom center of your screen, then click the Places tab.  Use keyword combinations such as "mens pants," "womens pants," "scarves," etc. and click the Search button in the window.  If you want to search Mature areas, make sure you check the box for mature.  Choosing a store to visit can be tricky; just because it's highly visited doesn't mean it's top quality.  Stores that aren't visited so much will often have deals in order to attract new customers.