Vectorfish tells it like it is, be "confident." remember, they want you or else they would not of made the offer. I would hike it up a bit but not too much, this is very realistic and the "hr" people expect a counter. this is only if you have not "agreed" on anything yet, hopefully you told them you'd get back to them re: salary. I'm sure you'll do OK Motor Fish. IMO, i'd rather have the higher salary initially then bonass.....
Try and get more vacation time if you can and get it on paper.
I just got a new job and requested 3 weeks vaca, when it came to take my vacation they told me 2 weeks I never got it on paper, I just sent it back with my offer letter!
VB