Utility Cycling - What mods do I need.

Hi everyone, new here and I'm going to be biking to and from work everyday. It's a 4.5 mile round trip. I'll have my large lunch box and water bottle. I want a spot to put my work jeans in so I can ride in shorts. Please fire away with what everyone is using or has used. Thanks!

Mount a Front Basket . or as I have, a pannier rack and a pair of bags..
front or rear.

Backpack, messenger bag, trunk rack or panniers.

I commute 4 miles and usually just go with backpack. I'll take the bike with small panniers if I'm grocery shopping after work or take more junk to/from work.

If you can't stand backpacks, a rack with trunk bag should be plenty for lunch+ jeans and leave room for other small items too.

I should of said I have a Gary fisher bike. I have a backpack but it is just for a water bag. How much do bags on the back usually go for?

$20 on up to (I dunno, maybe $300)

Try to find one with a suspended mesh back if you ride in the heat much. I spent $75 on my current backpack. Very nice, light comfy. Sternum strap and waist straps are important.

What do you guys use for picking up groceries?

Grocery store is on my way home so I often hit it everyday and just use my backpack. If I'm gonna stock up, as I stated earlier, rack + panniers.

Since the store is only a half mile from home, sometimes I wing it:

http://farm3.staticflickr.com/2623/3991211421_a57244234a_b.jpg (http://www.flickr.com/photos/lesterofpuppets/3991211421/)
IMGP1603 (http://www.flickr.com/photos/lesterofpuppets/3991211421/) by Lester Of Puppets (http://www.flickr.com/people/lesterofpuppets/), on Flickr