I went through the EMR list at [[http://en.wikipedia.org/wiki/List_of_open_source_healthcare_software|http://en.wikipedia.org/wiki/List_of_open_source_healthcare_software]] and tried out the ones I could get my hands on. Here's a summary of what I found.

Legend:
? - unable to verify
N/A - feature not available
F - crashes or doesn't work
C - limited functionality, bad interface
B - decent functionality, bad interface
A - decent functionality, decent interface

^ EMR ^ License ^ Platform ^ Scheduler ^ SOAP ^ Billing ^ Usability ^ 
| ClearHealth    | GPL | Web    | ?  | ?   | ?   | ? | 
| FreeMedForms   | BSD | Native | F  | N/A | N/A | F | 
| FreeMED        | GPL | Web    | C  | N/A | N/A | C | 
| GNUmed         | GPL | Native | C  | B   | N/A | C | 
| GNU Health     | GPL | Native | C  | C   | C   | ? | 
| OpenEMR        | GPL | Web    | B  | B   | C   | C | 
| OpenMRS        | Custom (GPL-like) | Web | N/A| N/A | N/A | B | 
| Oscar          | GPL | Web    | B  | B   | C   | C | 


As far as I can tell, it's a toss up between OpenEMR and Oscar. We'll need to take a closer look at both their billing systems to figure out which one is closer to what we want.