If you would like to create your own box upgrade guide for your box model, you can do so here!
In the meantime here are some links to off site guides:
Standard Sky+ Boxes
Pace V1
Pace V2
Pace V3
Thomson Sky+ 160
Thomson V3
Amstrad V2
Amstrad V3
High Def Sky+ Boxes
Thomson HD
Samsung HD
Pace HD
Amstrad HD
Amstrad 500GB/1TB HD