ATTENTION ALL NEWBIE WHOBIES!
If you'd like to just start watching Doctor Who, like just jump in all cold turkey...
My suggestions would be:
If you have patience and time and LOVE old 60's campy sci-fi: Start at the very beginning (first doctor)
If your attention span can only handle color tv: Start with the 3rd doctor (his run was the first in color)
If you'd rather skip to the newer/updated less campy stuff: Start with the new series (9th doctor)
Here are a few helpful links to get you all clued in on the wonderful world of Doctor Who.
My favorite companions of the Doctor:
K-9 (robot dog)
Rose Tyler (buxom blonde sidekick)