All of this is done on a rubbish spec laptop.
Roughly how good is a Mac for me?
A Macbook is far from a rubbish spec laptop. It's a svelte, sexy notebook that runs a far superior OS which with some tweaking can run all those other inferior OS's if you want. Then again, you can pretty much expect a response like that on a Mac forum.
As to how good a Mac would be for you? You'll have to just go see for yourself to determine that. Yes, we are advocates here, but sometimes we'll advocate sticking with Windows and all that the Windows world entails.
A Macbook would indeed enable you to communicate with your MSN and Windows Live Messenger buddies in some way or another (Parallels, VMware, bootcamp) while enjoying all of the fine kit that Mac OS provides. That Open Office and MS Office thing too.
Gaming, maybe not so much. Then again I only run one game which is UT2004 thus I'm lame but it runs fine on my Macbook. Other games, maybe not. For that I'll get a console once the economy gets better and I can afford silly things like that. Gaming rigs require a lot of graphical processing power. Expensive processing power. Expensive as Macs are believed to be in some ways.
However here is the succinct review: A Macbook is a highly portable, multiple OS running, powerful, convenient, quality notebook that is quite feature filled technology solution that is quite competitive with other non-Mac laptops/notebooks. It would be very difficult to go wrong with one.
Well, except for that Firewire omission. Wish Apple hadn't done that with the latest models. Glad mine has it.