There are so many excellent burger places in the Capital! If you want good burgers, you are going to have to come to P-Town:
Capital Craft (Centurion or Menlo Park)
Burger Bistro (Centurion)
DK Burger (Waterkloof)
Ed's Diner (Woodhill/Garsfontein)
Edit: Hudson's (Hazelwood) - thanks [MENTION=395]Wenzdayz[/MENTION], I forgot about them. See, Pretoria has all the best burger places
RocoMamma's is kind of crap by comparison.