I've been using Minis as my main computing machines for years.
I currently own a Core 2 Duo 2.4GHz (2010 model) and have the following programs running at startup :
Libreoffice, Safari, iTunes, Mail, Twitter, VLC, Pixelmator, Thousand (2ch reader), uTorrent, Terminal, Activity Monitor, Text Edit, Console, and a bunch of widgets.
Safari often has 10+ tabs opened when I browse.
Sometimes, an extra program or two will be running on top of these.
Never a hick-up.
RAM is maxed out to 8 GB, though.
So I'd say if you already have a monitor/keyboard/mouse handy from your old PC, the Mini is definitely a viable option.
Upgrading RAM is pretty much as easy as putting a couple of coins in a jar.
Open the lid, throw the RAM sticks in, close the lid.
Just make sure you have the right kind of sticks, but there are tons of sources which will tell you exactly what you need.
i have the same model, i upgraded the RAM to 4GB months later but now i'm thinking to max it out to 8 GB, do you recommend that? or should i wait for when Minis come with SSDs as standard?