Working with Time Machine running

Question 1 - I'm running Snow Leopard on a 13" MacBook. When I had Leopard, Time Machine would run for just a few minutes and pick up the "new" items. Now, it seems Snow Leopard does a backup of my whole hard drive, taking hours. Is there a way to set it to just back up the new information, or do I have to start doing backups overnight while I sleep?

Question 2 - Can I work with email, browsing, etc. while Time Machine is running or do I need to leave the PC alone?

TIA.

Q1: When you say " ..... It Seems ..... " what does that mean ? What do the logs say ? The log indicates how many GB will be backed up on each backup run.
Has your first backup on SL been completed successfully, because that can take a long time if you are doing it through the air

Q2: I never stop using any app. when TM kicks in, it runs in the background and does not eat up a lot of resource so I hardly notice TM is running

Cheers ... McBie

1. Have not experienced TM functioning any differently than it did with Leopard. Agree with McBie, sounds like the first complete backup has not completed.

2. The only issue I've experienced with TM running in the background has been a network slow down during either a) the first full back up or b) the first backup after I just downloaded a GB or more of video from iTunes that is being backed up. Those are the only times I make a point to have it backup after I have quit for the day.