Biker - the price of a mac equivalent could be a put off but if you shop around there are decent deals and the Apple site do good deals on repair items for sale (they are in great working order and all the warrantys etc but just second hand)
http://store.apple.com/us/browse/home/specialdeals
That link is for the US store, here is the UK store link.
http://store.apple.com/uk/browse/home/specialdeals
Another vote for the 'Special Deal' section from Apple. The last two powerbooks I have purchased were 'reconditioned' machines from the UK Apple Store, one purchased in 2006 the other in late 2007, the former worked fine until about two months ago when the hard drive gave up the ghost, not the end of the world and (in that machine anyway) easily replaced. The machine from 2007 has had a much rougher life, has been to far off parts of the world, different climates, bashed about film sets and building sites. It works fine, one of the 'apple' buttons is missing but still works if I press hard enough, I could get a replacement for it (or indeed almost any other part from
http://www.thebookyard.com/ if I felt the need.
"...I do like Apple hardware but its the Apple users I have a problem with having had to support them in a commercial environment..."
This is true, I remember turning up to various gigs back in the late nineties early 2000's and the look some of the IT folk would give me when I pulled my old Apple Pismo out of my backpack said it all, I always tried to be nice though, but you could tell that the 'cult of mac' had caused them no end of problems in the past. I don't get that so much these days though.
"...you can't really upgrade them, your stuck with a model until Apple launch a new one..."
I don't doubt there are probably applications that I could be running (Autodesk perhaps?) that may have required me to upgrade my machine, but I run a browser, I check my email, I write documents, I listen to Radio 4, play music and I backup and view my digital photos. My laptops have been doing this happily since 2006/7, no upgrades required.
I only recently installed the all new all singing OS 'Lion' which theoretically should be pushing my machine to its limit. It isn't, it works fine, the only thing I have noticed that is a little slower is start up time for the default image viewing software, but I use Picasa so that doesn't matter. However the next OS upgrade which seems to be mostly a tidying up of the current OS will not run on my machines (not officially anyway). So if I want that upgrade, yes I'll need to buy a new machine.
But I won't, these ones work just fine.