Changing column width

I’d like to change the left column width to 170px. Is there any simple way to do this?

I did manage to make a similar change to a 2 column version of the webpage template, but I’m missing something on the 3 column WordPress version. I can get the home page to look OK, but when I go to the “About” page things get screwed up (column overlaps text). I know it’s all about margins and eventually I’ll probably get it, but I wonder if there’s some simple rule to follow?

Also is there a way to add or remove links from the left column. I know it’s coded into header.php but I don’t know where it’s picking the “about” link up from and I couldn’t find anywhere on the WP admin page where I could add/delete left column links. I can hard code them into the header.php file, just wondering if there’s a better and easier way.