Hi Willow: You do know the most important thing though: The computer is there for you to use as a tool.
Your primary need, it sounds like, is reliability (can't be faffing with downtime) and ease of use wrt communicating with others.
I also note you sound somewhat peed off with sluggish systems and you want something snappy. My guess is your old Windows box is driving you mental.
(No, I on't hold shares, however Apple has gone up something like 300% in the last couple of years. Damn, missed that trick. Apple users tend to be annoyingly evangelistic, as you can see - but that's only because they are so happy with their equipment and the ease of use of the OS).
If you spend a lot of time on the machine, I would recommend the largest screen size you can afford as that will make more difference to your life than processor speed. If you play mainly with text you don't need to go crazy on RAM, but more is definitely merrier. I am about to take my laptop from 512MB to 1GB (for about £45) as I hope to be getting a digital SLR (which throws out bigger files) and maybe a camcorder when baby comes.
You are definitely right in thinking of going with a laptop. You can use it in whichever room looks least hellish, and you'll have no wires trailing everywhere (except the power lead)... If you get an extra power adaptor at the same time, you can have one upstairs and one downstairs and you will always think 'what a clever person I am.'
Getting your house wireless is DEFINITELY going to make you even more smug. It very much changes the utility of your laptop and means you can simply run away from mess / noise / distractions and continue working wherever. It also means guests / colleagues turning up with laptops can be on the Net within about 30 seconds of knocking at your door.
Apple sells a wireless gateway thingy called the Airport Express. If you plug a cheapo ADSL router into it, it will give you a wireless home at 54Mbps, PLUS a printer port (so you can wirelessly print PLUS an audio output so that you could connect it to a HiFi and select music from iTunes on your laptop but listen to it on proper speakers instead of the little ones onboard the laptop.
If you think doing all that sounds v. complicated you are wrong. You will be able to 'rip' a CD of music onto your laptop with about 15 seconds of instruction. iTunes is very easy. There are also admin utilities to talk to the Airport Express so that is also easy to setup. If you want to go down this route, you should check / read up about router compatibility to make sure whatever you buy will work with your Airport Express.
Incidentally, the network speed in your house is not really the bottleneck when dealing with incoming / outgoing documents / powerpoint shows etc. In my house, my network is only 11Mbps and it is PLENTY fast enough for SERIOUS use. No, the bottleneck is in the size of your ADSL pipe (say 512kbps / 1 Meg / 2 Meg connection) and the sluggishness of the PC / laptop opening /closing Word / Toggling to PowerPoint, searching archived e-mail etc. etc.
I am glad your family has some Mac exposure through dh at work. If he gets to use it I'm sure he'll tell you that after the initial 'running in' period where you need to learn how stuff works in a 'Mac world' their systems are a joy to use.
Microsoft make Entourage for Mac which I think is Outlook Express (with contacts / diary built in). I just use Apple's Mail / Address Book / Calendar app so cannot tell you how it performs. I pick up hotmail through a Web browser but there are some sneaky httpmail plugins you can use to read your messages in your ordinary mail app instead of online but I've found them somewhat unreliable.
Hope that answered some of your questions. If you live in London there's a lovely big Apple store with gleaming gems of fantasticness in Regent Street.
Verbal diarrhea or what ?