Applications won't transfer over a network easily because of registry entries for settings and registration - they aren't copied with the files. As for data, Callum's right.
And yes I am happy to do that
Also with regards to the psu, they're about £15+VAT plus whatever labour he charges so shouldn't be an issue.
Keeping hard drives is a good idea, but if it's IDE you will struggle to connect it as most PCs now only have one IDE channel (which would usually be connected to the optical drive)