I wanted to drop in right quick and say how much I really really really like Wendy's salads. I am the pickiest person when it comes to my lettuce and they have fantastic salads. I strongly encourage you to either get a side salad or the regular salads (there are different options).
I will tell you a little secret though. Even though you are thinking you are making a better decision calorie wise by eating a salad vs a 1/4 lb hamburger and fries that is not always the case. I had a BLT salad with a large rootbeer the other day and compared it online to the 1/4 hamburger medium fry and large rootbeer. The salad came in with 30 more calories than the burger only because I used 2 pkgs of ranch. I did not check fat and sodium, but I assume the burger had more in that department.
Either way, eat the salad. It is fantastic. You don't feel like a big greasy blob after you eat it and it gives you the greens you need....even if you do smother it in ranch.