Is a USA master degree equivalent to mphil in the UK? I have a MS in marketing. Any idea how to find out? Than you

Your USA Masters degree should be enough to get you into a UK PhD programme (providing that your GPA for your bachelors was around 3.3 or above). Many UK departments insist that all prospective PhD students register for an MPhil first. At the end of the first year students are assesed and most are usually allowed to change their registration to PhD, only those not considered good or commited enough to continue will be asked to submit their work for an MPhil. Doing a PhD this way doesn't take any longer (because you never complete the MPhil, the work done in your first year counts towards your PhD). It also gives you a chance to finish with an MPhil at the end of one year if you decide not to continue.

hmmm. my BA GPA was 2.8 but i got a 3.2 in my MS degree, iing also have solid 10 years experiance 8 of it my field. will that count for anything?

Yes your experience will count.