Yep, UPDATES for both the mapping software and navigational software can be expensive. As these gadgets get older too, say 3 weeks out of the box (sorry not really) they are outdated quickly. There is around a 2 year lag to in getting info from real life onto the maps so as an example the latest update for mine which was August last year would have had details that were current in around 2005.....
The Garmins are sposed to be really top of the range and supposedly will guide you across the vast interior where no roads exist.... But the ability of these to acuratley guide you depends on the quality and CONTENT of the acual mapping software, the navigaion side being done by the GPS....
My advice (not that you wanted it but your gettin it) would be to either keep the Garmin for a toy and buy a new one for $300 WITH BETTER SOFTWARE ALL ROUND....

These things like all this modern whizz bang technology "ages" so quickly....Soon these will come free in "Blue Hills" (Cereal) packages.... This is an area where planned obsolescence has a strong marketing strategy...A bit like mobile phones, mine does everything and I only want it to make calls.... In the USA did you know you can buy mobile phones from vending machines $10us ea, use it and throw away, no provision to recharge it.....
To answer your question Dave yep even if you buy one with updates current today it will still be a cuppla years behind reality. However they do take "planned" roadworks into account when doing the mapping...

-- Edited by Basil Faulty at 15:18, 2008-08-31

G'day Basil & Dave..
When you get a chance, check out a web site called 'Shonky Maps". Apparently there are ways to up date a GPS without the extravagant cost.
I have never been there, as I don't as yet have enough 5 cent cans'n bottles collected to buy one.
Have placed a Fathers Day order, but don't think I have enough fingers to cross.

Great to see you lovely blokes entertaining this forum.

If he has a computer he can update his Garmin online at no cost.  I have several Garmin's (why is another story) and recently updated them all including an old GPS12.

I have Shonky Maps loaded in all my Garmin's as that is my basic mapping package.

Now if it's at all shonky why wasn't I told (to quote Dorrie Evans)....
Looks brilliant to me.....

 a big old welcome to you captain, at last we have rank with us lot, look I agree, that information apparently was passed to the gentleman in question as well but when he went to register or whatever it takes he was presented with the option of "buying" an update, I dont know the absolute full details, as it was passed on to me by an older feller and he was a little confused (arent we all) by modern technology, the wizzbang gadgetry that was in the little box was perhaps his first foray in to modern technology, bloody mongrel barstards,if one must update these things at (to many, certainly to him), is great cost then it turns out to be incorrect and behind the times why are the companys taking advantage of people such as him and me and you, oh one other thing that I found whilst "googling" shonkymaps, this is the same topographic map that was sprouted as the be all and end all of modern desert and outback maps, in one of our forums earlier,  it is currently being "sold" on ebay for an enormous ammount, just shows that one must keep communication and all eyes open, otherwise ones money is gone as is one old fellers that I could not help, but hopefully many more will read this and the mongrels will be brought to task by technology itself. if anyone is going to or has downloaded these maps would you please let the forum know how you got on and what the results are like.