I agree with just adding a new circuit instead of replacing the existing one. If you do that, you might want to consider making it a 240 volt circuit. One plus with a 240 volt circuit is that the AFCI requirement does not apply. One NEC rule (210.6(A)(2)) does require the circuit be for no loads smaller than 1440 VA. You can get around this limitation with a UPS which is 1440 VA or larger. The "208" volt models would be the ones to choose.
This will double your added capacity. You will be limited to only running 240 volt devices. Virtually all computers handle either dual voltage by a switch, or an autorange from 100 volts to 240 volts. You'll still have the previous 120 volt circuit for everything else (but for best surge protection, do not connect anything between devices running on different circuits, unless it is an optical or RF connection).
The cost impact of a 240 volt circuit is the price difference of a 2-pole non-AFCI breaker vs. a 1-pole AFCI breaker (probably about the same), the panel space this new breaker takes up, and a few inches of marking tape to make the cable in the wall legal by wrapping black, red, or blue around both ends of the white wire (since it won't be a neutral on a 240 volt circuit).
A couple suggested UPSes for 240 volts:
For 2000 VA ... http://powerquality.eaton.com/PW9130G2000T-XLEU.aspx?CX=3
For 3000 VA ... http://powerquality.eaton.com/PW9130G3000T-XLEU.aspx?CX=3
If you choose these UPSes you might want the NEMA L6-20 "twist and lock" type outlet. Your electrician should know what "L6-20" means (if not, hire a different one that does). These UPSes give you 8 C13 type outlets that cords which plug into computer towers use, so all you need is to get some C14 to C13 power extension cords).