I have to agree with everyone else. I've heard the same thing and people are always trying to fix me up. I won't do it for alot of reasons. But here are the basics (most have been stated above):
1. 2 wrongs are worse than 1; 2. It would infuriate my W. She has taunted me to do it (early on but not in the last 2 months), but I know it was to give herself justification for her A; 3. Even if it is "not ready for anything serious" by both parties going in, it can turn on a dime. Either your emotions or her's (date) emotions could get run through the ringer; 4. You've seen "Fatal Attraction", right?
Don't do it. You will feel better in the long run and I would assume you would have a much better chance of rebuilding marriage w/o dating.
Going out w/ a female friend, who is just truely a friend, is different. I have those. My W knows who they are and that they are just friends. But still, what other people see will get reported back to our spouses. Then it is damage control and major backslide (defending your self) or portraying the attitude, ifyou can do it so can I. It just raises the bar to a whole new level.