If anyone is foolhardy enough to join me with Core and proprietary graphics let me offer all the advice I have:
If your Core won't boot edit the GRUB command line (at the GRUB screen instead on selecting your 
Core install and pressing <enter> press <e>).
at the end of command line (with should contain 
ro quiet or 
splash) add 
vga=795 and/or 
nomodeset...
If you can boot you're going have some fun installing your proprietary graphics without blacklisting nvidiafb the 
Debian way. Inserting 
blacklist=nvidiafb into the GRUB command line will 
not help.
[*]
su to the superuser account.
[*]If it exists rm / etc/modprobe.conf (it probably won't exist)...(remove the extra space after the '/' and before etc).
[*]nano / etc/modprobe.d/nvidiafb.conf...(remove the extra space after the '/' and before etc).
Add the text:
<ctrl+o> and <enter> to write 
out the file, then <ctrl+x> to e
xit.
[*]Reboot
Installing the proprietary driver with 
smxi should be a lot more straightforward. Hope this helps.