Purchasing a Mac Mini

My PC that currently acts as a server for the house is having numerous issues and will need to be replaced by something in the near future. I'm currently debating whether or not to purchase a Mac Mini as it's replacement. Currently I own a PowerBook G4 and it's the most popular computer in the house, and it would be nice to have things like photos and music stored in an easily accessible and centralized location. I run Linux Mint on my laptop as I've noted in other posts and I am perfectly happy with it. I plan on doing the occasional DVD rip to divx, burning CD's and DVD's, and heavy torrenting.

By way of comparison, here are the specs on my current PC:

• AMD 64bit 3000+ single core processor overclocked to 2.2 GHz
• 3GB RAM
• MSI K8N-Neo2 motherboard
• nVidia 6600GT AGP graphics card w/128MB
• 250GB SATA HDD
• 80GB IDE HDD
• 500GB External USB HDD

I used to be a regular gamer, playing WoW and CS:Source frequently. Now I do my gaming on my Xbox 360. A few questions:

• How difficult is it do upgrade the RAM in a Mac Mini?
• How is the performance?
• I would run XP in VMWare for those times when I absolutely had to use Windows (work, etc). How is performance?
• How is the power consumption as compared to my 450 watt PC?
• Anyone wanna push for a custom built Linux box over the Mac?

I believe that's all. I'm open to any and all suggestions.