Co-worker dating is a double edged sword. Some of the hottest, freakiest chicks i've had i have met from work. Its like u can build sooo much sexual Tension with them because u see them EVERYDAY for 7 freakin hours. U can slowly, subtly run game. Plus, if u are an excellent, take charge worker who treats everyone with respect they will sort of look up to u. Eventually, even hinting at a hookup will cause all those feelings to explode. Thats why they can be such sexy freaks.
ALL THAT SAID... when/if it goes bad... it will be BAD. BAD BAD. She will know ur personal life, she can spread your business around (possibly killing your chances with other girls at work) and may try to get u in trouble for petty things. Think of your rep at work before u try anything. If your willing to lose it and it wont affect your job performance than go for it.
And yes my example is extreme but trust me... all that sexual tension building could leave some chicks mentally scarred if they were looking for a boyfriend and u gave them a ONS