I like the name, but that could be because my Mother's maiden name is "Markham", so I suspect I am biased. When you get right down to brass tacks though, what matters is not what other people think of it, but whether you and your partner like it. Another thing to keep in mind is whether the name is one that other children are likely to see as an object for teasing. I can't see that problem with this name, but it would probably be shortened to Mark by a lot of people.
Have a look in both your families as well, sometimes you can find a nice name in your past. We named our son George for my Grandfather, and if this baby is a boy his middle name will be a family name too.
Rachelle, NZ, son George 10.12.02, Ian 15.06.04