What about the Replicators from Stargate SG-1?
Ooooh, that's a tough one. It depends on what scale we're talking. Space battles, I think the Zerg would win, for the same reason they would win verses Borg cubes. Zerg fliers, while smaller, are far more maneuverable and numerous. Sheer numbers, given enough of them, can always defeat superior size and fire power. That's why it's called a brute-force attack.
Ground battles, I don't know. In terms of pure melee combat, I think the Zerg would win, because they are capable of reproducing at a similar rate, but they are far more varied in species. But, the Replicators are comprised of thousands of microscopic nanite machines, any number of which could infiltrate a Zerg body and wreck havoc from the inside. Additionally, the Replicators, in both the SG1 and Atlantis series, have demonstrated very powerful adaptability in response to unfavorable circumstances, probably very close to that of the Zerg hyper-evolutionary virus, if not equal. It would not take long for the Replicators to find a method of attack on a microscopic level that the Zerg would have difficulty combating.
A good example is the Atlantis episode The Real World, in which Replicator nanites infected a character's body, and then began harvesting various elements from within the body to be used to make more of themselves.
Remember, the Replicators are purely mechanical, which means the Zerg cannot assimilate them. The only possible way that I think the Zerg could gain an advantage of over the Replicators would be if they evolved a strain capable of producing EM pulses.