Slow OS X?

Hi! I'm kind of new to Mac OS X. I've got my 2.26 13" MacBook Pro about three weeks ago, and I'm feeling my Mac is getting... slow.

The time it takes to boot is kind of high, between 30 and 60 seconds. The waiting is kind of frustrating, and I'd even dare to say it's worse than a Windows XP's in this period from installation.

Next, the OS itself seems kind of slow. For example, I always feel I get some kind of a lag when I'm typing. Or at least, I'm 100% sure it's (way) slower that the Windows 7 I run on Boot Camp. I've taken for comparison Yahoo! Messenger, which is the most widely IM client used in my country, so the application which starts at log in, and stops at Shut Down. On Windows 7, it's smooth, the typing is instantaneous. On OS X, not only the typing seems worse, but the application itself. And let's say it's because the application is in BETA stage. But the text I'm typing here using Mozilla Firefox seems to appear slower, less smoothly that it does on Windows 7's IE8.

Is there anything I can/I've got to do about this?

Any help would be appreciated. Thanks in advance!