Tell me a bit more about Linux! Can you use many features you can use for windows or mac?
It depends upon what you do.
Linux is an open source operating system kernel, a linux distribution is the linux kernel with a bunch of software compiled ready to run. Common distributions include Debian, Ubuntu, Fedora, SuSE, Mandrake (I think now called Mandriva), Red Hat Enterprise Linux, CentOS (a free RHEL clone). Some are a free download, some you pay for.
There are several desktop environments that run on top of Linux - the two major desktops are GNOME (what I use) and KDE. Both are free, and included with most distributions, and you can run apps built for one desktop inside the other.
While many major software applications, such as Photoshop and MS Office, do not run in Linux (though some can through WINE which emulates Windows system calls) there are free open source alternative to most of them.
The GIMP is a photo editing program. It does not have all the capabilities of Photoshop and does not have as many custom plugins available, it is more than sufficient for many people.
For office needs, there are several solutions. Most people use Open Office. I myself do not like Open Office, I use Gnumeric for spreadsheet needs and LaTeX for word processing needs. LaTeX is type setting software, you can output to ps, pdf, even xhtml with full MathML support. For reading a word document, I just use AbiWord. For creating a word process document someone else needs to edit, I again just use AbiWord (which will save the document as an RTF file but put a .doc extension on it, people who use MS Word never know the original was RTF and not a Word document).
For presentation needs, again I use LaTeX - to create a PDF slide show. PDF slide shows can include multimedia (such as movies) and are better IMHO than powerpoint because all you need to view them is a PDF reader, and Adobe Acrobat is available for just about anything out there.
You can play with Linux on your mac without installing anything, both Ubuntu and Fedora make live DVDs available that you can boot off of and fool around with at no risk to what is installed on your hard drive (just don't ask it to format your disks - because they will if you ask them to). Note that running off of a live DVD is going to be slower than if it is actually installed to your HD.