right i just sorted this problem out.
turns out my bios settings had gone back to stock (asrock "feature"

) but this caused my vista to konk out on load up with the bootmgr missing problem.
now for some stupid reason vista had the bootmgr on a different drive to the main boot drive.
to cut a long story short, all i did was fire up my lappy which is running vista 32bit, and copy the bootmgr file which is in the root of lappys c drive to my usb drive. i also copied the hidden boot system folder found on c:\boot.
copied all that to usb drive. then booted up using erd commander on my shafted pc and copied those files and folders over to the c drive and im now typing this message on the pc which was shafted.
2 things this shows, 1: vista is stupid. 2: 32bit bootmgr file works on 64bit vista.
tried that crap where you run the vista dvd and select repair and then use command prompt and the bootrec /fixmbr and /fixboot etc and bcdrepair crap but nothing worked other than manual copy job.