I should have added, as Skit75 rightly did, that if you can't enable onboard graphics and the GT 610 at the same time, then two GT 610s will get the job done just fine as well. Windows 7 & 8 play very happily with multiple graphics cards and the "Screen Resolution" setup will simply detect all the monitors and allow you to arrange them however you like regardless of where they're plugged in.
2x GT610s is also probably close to the cheapest way of doing it (assuming you can't enable your onboard graphics).
On Nvidia cards, you don't get four displays from a single card until you get to a GTX 750ti, much more expensive than 2 GT 610s. I'm not sure where they start on AMD cards, but they have the additional complication of requiring native display port or active adapters for 3rd and/or 4th displays (depending on the GPU generation). I think you'll easily spend more than 2xGT610s before you find a single card setup that meets your needs.
So, if you can: 1x GT 610 and enable onboard graphics in the BIOS. Failing that, 2x GT 610s.