GPS Newbie

After a good while pondering over getting a GPS, I'm finally seriously considering taking the plunge. The problem is, I know so little about them.

 What I want from a system is 3 things:

1. To be able to route plan using either Ordnance Survey (or similar) mapping at home on my computer, or by uploading routes from guide books or websites.
2. To be able to walk with the device whilst viewing Ordnance Survey (or similar) style mapping, and obviously be directed as to where I'm going!
3. To be able to review routes at home afterwards.

Looking online, I'm drawn to the Garmin Oregon 450, which I've seen online for £350, including full UK OS mapping (1:50000 scale). Would this do what I want? Is there something else that would do what I want better, or for less?

Sat Map Active 10+ comes with full GB 1:50k. The active 10+ comes with a one year subscription to their online mapping/route software where you can create and share routes. Current prices on Amazon is sub £300.

Personally I use it with Memory Map software to create routes and download to the unit, however I have created a route on the unit itself and it was a breeze.

Definitely worth considering - I was looking at various units for over a year before buying the Sat Map and I am very pleased with the unit.

http://happyhiker.co.uk