Could be that the 3500 doesn't have the same hard drive 'quirks' as the 3400 (I hope so - it'll make life sooooooooooo much easier for you) - not 100% sure though so probably best to take it as a 'if things start going screwy then maybe...' bit of info

No problems sharing the boot disk (if I can find it - in the middle of trying to move house so a lot of things have been packed away)(if I can't then I should be able to remember enough to help out). From memory there are some drivers out there that allow USB drives to be accessed via DOS...and then everything gets very easy

Wish my 3400 had cost $20