MBP Memory use?

I haven't been super-good about monitoring system performance, but I found a few specs today to be a little disturbing.

I have a MBP 2.5ghz machine, with 4gb of memory installed. Currently I'm actively running Adium, Safari, Mail, and activity monitor, along with whatever native processes there are.


For some reason, though, these programs are using up 3/4 of all the memory I have (3gb... 1 gb inactive). I also noticed a 45gb VM (It's a 200gb HD).


Do these numbers seem right? I had a powerbook g4, with 1.5gb of RAM, and I ran the same programs without a hitch. I never looked at the activity monitor for that, but I just feel like the current machine shouldn't be using so much RAM...