I dislike the term "IT Guy". I also give or ask for more details when someone's work is described as "s/he works with computers!". I have no clue what it means when someone is tagged as "working with computers". I used to dislike the term so much that I actually quit the job profile completely to go freelance designer. I am happier now. I am often reminded of this quote by Dijkstra when I think of the "IT Guy" Computer Science is no more about computers than astronomy is about telescopes. - EW Dijkstra

I have a MS in Computer Science which I got in 2005. I would definitely recommend getting a MS. While you are constantly working, it doesn't look like a big deal to have a MS- but in case you ever go on a break from work a MS will stand by you in good stead. And its always better to have done a MS earlier in life than later. A good MS with diverse courses and an in-depth thesis is definitely worth more than two years in the industry. Having said that- I did my MS after working for three years in the industry after my Bachelors under-graduation in Computer Engineering. And that surely helped me pick the right courses and a thesis topic.