double din sat nav / hdd questions

I've just bought a mk1 vrs and I'm thinking of fitting a double din unit with sat nav. Which is a good unit for a decent price? It's been a while since I ventured into the ice market.

second question is can you fit some sort of hdd under the passenger seat or in the glove box to store music on? There may be double din units with this capability but i'm not up to speed.

Cheers in advance