The lead mick linked to is the incorrect way round, it's HDMI to VGA only (not sure how well that would work with all monitors either!)
IMO you won't be able to do it. there are devices for sale that claim to be USB video adaptors, but from the couple I've seen they are not suitable for video or games and just about passable for presentations. To do it half way decently you'd need a VGA (analogue) to HDMI (digital converter) which will be expensive, or you'll need a VGA to composite converter which is going to be low quality (composite is always low quality it's ok for video but you won't be able to read any text on the TV)