Ask HN: how bad are trademark conflicts for startup names?

After spending a lot of time/effort agonizing over names for my startup, I recently identified one that I like, and that I might actually be able to obtain for a reasonable price.

To my dismay, a USPTO trademark search turns up the exact name as an existing trademark. The two businesses don't seem that related - mine is a consumer web site, the existing trademark appears to be for some software related to IT management. It is owned by a 5th tier IT consulting company. (In other words, obscure product.)

I also noted there was at least one other consulting company using nearly the exact same name I had in mind. (They get #1 on Google.)

Both of these companies presumably have deep enough pockets to cause problems for me. Does it matter and how much should I expect to pay a lawyer to check it out for me?