Yes something is certainly wrong!!!!
I have 2Mb broadband too and the Download for Vista is 3-4 Gig depending on if you have the 32 or 64 bit version.
If you can download 3-4 Gig in 30 minutes on Tiscali then I am certainly going to change my ISP to Tiscali!
I would guess it would take about 20 hours plus to download vista. I suggest you try and find it as a Bit torrent download which will make life easier.