Hey...
Have just booked RTW tour and wanting to get backpack asap...not going until Jan 2011 but need to be sure of the best one as going for a year.
Iny links/ suggestions would be awesome.
Also, travelling South America, Oz, New Zealand, Fiji and Asia....anything not to miss out on then please let me know as me and my mate are party animals!
Cheers Leanne
Try Kathmandu.
Eagle Creek have a good range, I actually prefer their packing systems.
A big consideration is size. If you want mobility, it is best to keep within carry on size limits, 14 x 9 x 22 inches.
Carry on will not only allow you to bypass the baggage turnstiles, it will also give you the security of having your belongings with you.
Quoting Curt1591
A big consideration is size. If you want mobility, it is best to keep within carry on size limits, 14 x 9 x 22 inches.
As the OP is going for a year a "carry on" size wouldn't be big enough.
it will also give you the security of having your belongings with you.
Does not having checked in baggage give you secuirity? I always have che3cked baggage and have never felt insecure about my belongings. Things like camera, money, travel documents etc can be taken in a small bag or daypack and carfried on board.
I haven't heard of carry on luggage getting lost, or sent to a different destination. Rarely does it get damaged.
But, beyond airlines, one might be taking more local forms of transportation. This is where a lot of pilfering can take place.
Carrying a lot of stuff is, more often, less of a convenience and more of an anchor.
No one is going to pack a years worth of stuff, no matter how big a bag one carries. 
yep ur right, carry on always has its advantages and if ur traveling in the southern hemisphere around January u won't need to pack to many warm clothes. U will also find that u can by most things such as toiletries and clothes at your destination.
Buy a small pack and travel lite.
Anyways not sure on what size of pack u are looking for however the following brands are durable of high quality and have a wide range to choose from, try:
http://www.macpac.co.nz/Product-Support/Packs
http://www.ospreypacks.com/
http://www.karrimor.com/
https://www.mountaindesigns.com/index.cfm?
Here's an obscure pack, but a real monster for the carry on traveler: Aeronaut
This will be my wife's replacement when her Kelty dies. It's not cheap. But, do you want to trust a cheap pack to last a year on the road?
This is the bag I've used for a couple decades. MLC
I wore one out, took it into a Patagonia shop, and was handed a new replacement.
Quoting Curt1591
No one is going to pack a years worth of stuff, no matter how big a bag one carries.
Of course not, but being away for a year one needs to factor in the seasons. While I'm not suggesting packing clothing for summer, winter etc., clothing would need to be bought on the journey for this - and would need to fit into whatever form of luggage one had.
With clothing, I go by the rule of one on the back, one in the case and one in the wash.