vejita, I've got a Dell Dimension 4200, so there may be some simularities, but definately not as high spec as your machine! I cannot say which distro will be the most compatible with your machine - best thing to do is look at the distro websites - many of them have a hardware compatibility list or database.
The first distro I tried was Knoppix. It boots and runs from a CD without touching your hardrive and is good for checking that your hardware works ok with Linux. Also shows you what Linux is like. Download here
- on my Dell this was very successful (and fast, but that may have been my 50x CDR).
I tried the Suse Linux evaluation CD - another run from CD linux, and this ran well, if v. slow to load. Based on that I installed Suse linux.
You will have trouble with the NVIDIA card if you want to use the NVIDIA binary drivers - but that will be the same on any distro!
Hope this helps a bit - and good luck with whatever distribution you decide on!