Is there any system maintinance i should perform on a certain basis? Like in windows, theres Disk cleanup and disk defragmentor? Is there something that has to be done to keep my computer from slowing down?
OSX defragments automatically, so no worries there. As a regular procedure, I would at a minimum add logging out or better yet rebooting every few weeks. This clears the virtual memory cache files that tend to build up and slow things down. I'm also a huge fan of AppleJack, a maintenance tool run from single user mode. It automatically checks the disk for any errors, repairs permissions, clears caches, looks for corrupted preference files and does those Unix cron jobs that won't get done unless you leave your Mac running 24/7.
If you have your Mac on 24/7, then Mac OS X automatically runs a daily, weekly, and monthly maintenance schedule. It's best to run Repair Permissions after a large updates or installations. It isn't necessary to defragment in Mac OS X.
and on the other hand.....there are lots of people who never do any maintaince at all and their machines work just fine....not having to constantly do maintaince is why a lot of people use Macs in the first place