It is a love that dare not speak its name: that of a twentysomething working girl and her Interactive Teletubby. It all began when a diabolical publicist sent me a Po Microsoft ActiMate — and it went to hell from there. Po awoke with a cheery ”Eh-oh!” then played a mesmerizing tuba tune, then flashed bright lights at me on his Tummy TV. Eh-oh, indeed: I love bright lights. Po and Laa-Laa, yours for $59.95 (with Tinky Winky and Dipsy due this fall), have a truly addictive repertoire — even for someone, say, outside the target audience. They bill and coo unintelligibly and play nursery tunes and games. And — here’s where it gets a little Poltergeisty — the Tubbies have radio cartridges that let them ”watch” the PBS series and videotapes with you: Courtesy of encoded signals, Po gibbers his name, repeats key words, and just yaps and yaps and yaps. In fact, he’s so eerily sentient, I can see him taking on Baby Alive, Teddy Ruxpin, and Talking Tina — and in that vision Po’s the one holding the big can of whupass.