Unless you can see the other guy's hole cards, you're never getting 7 to 1. Best case is 9 to 1 once you consider his chances to out-flop you or suck-out.

Hence, I tend to go with the 5% rule calling a first bet and I'll make loose calls for up to 10% if there is already money in the pot.

The other consideration here, is how often can you pick-up the pot without hitting a set. I think calling to hit a set in NL100 or higher is giving up too much value. At least 5-10% of the time, you should be playing a little post-flop poker.

BTW: I'm all-in here. You're in good shape against his range.