Mac minis; old vs new

Mac Mini's look neat. I'm watching the classifieds and craigslist to keep an eye on them, and make my move to Mac.

Since i'm new to Mac, i'm not sure where to go.

The old G4 MM are definately affordable, but then i also have interest in the intel core 2 duo as well, as I don't believe the G4 are dual core ?

I am also not certain what OS to consider, but I think Leopard or SnowL would be advisable.

My uses would be primarily;

- torrent box
- htpc using xbmc
- hosting some apache, some blogs, a forum, and video / audio streaming. <Low usage.>
- probably doing a bit of video editing of my own recordered movies, once i figured out the OS more, and some of the apps.

If you those who are experienced with the hardware can point me in some directions. Also, what kind of ram usage might i need for OSX, and if you're recommending earlier models, can it be easily upgraded like my PC ?

A couple points from me:
1. The Mac Mini G4s aren't dual core. Also avoid the Intel Core Solo models. They are slow, and I wouldn't recommend them for the uses you suggest.

2. From having similar specs in my MacBook to the base 1.83GHz Intel Core Duo, I can tell you I wouldn't recommend getting anything slower than it. Firstly, if you want to use xbmc, edit and watch videos, especially on a big LCD, the newer video card and generally faster everything is necessary.

3. OSX Lion is coming in the next few months, so I'd definitely get a Core 2 Duo model, since the Core Duos like mine will be left behind with Snow Leopard. Perhaps paying a bit extra for the future-proofing of the next OS would be a good idea.

4. The original MacMini is easy to upgrade, once you crack the shell. That is a little difficult without the right tools. However, there are tools and videos available online. The RAM, optical drive, HDD are all upgradeable, the processor isn't. When buying one of these, I'd recommend buying the best processor you can, for that reason.

Hope that helps a bit!

I have little to add to 613's excellent advice. In the case of using XBMC (though I recommend Plex over that, which is a Mac-focused fork of XBMC), if you want hardware-accelerated h.264 decoding, you need a model equipped with the NVIDIA GeForce 9400M, GeForce 320M or GeForce GT 330M GPU. These are the only GPUs that Apple has released the necessary frameworks publicly for anyone to use hardware acceleration with. Anything older, and you plan on playing HD video, expect poorer performance with 3rd party apps.