I used 2 SD cards, 512mb and 2gb. I formatted them with FAT file system and FAT32 file system, just got the same sd card error message.
My unit came with V2 maps, no postcode input at all. The option is there to input postcode/town, but does not let you input it.
V3 maps £170+VAT from dealer, £99 off Ebay, so I just downloaded V3 maps from piratebay, not gonna stick it on until I they swap the unit.