Do you need free weights or are machines as good?

[DazedandConfused]

Over the last couple of months I have joined a gym and started working out 3 times a week to try & gain some muscle mass.

I'm currently just using machines in a circuit at the max weight I can do for 5 reps and then repeating 5 circuits.

Not sure on the proper names but the machines are (in the order I normally do them):

Bench press
Pec deck thingy (backwards & forwards)
Seated row
tricep extension? (straighten your arm in a stabbing motion)
bicep curl
overhead press
weighted sit-up machine

A few questions:
As a routine how does this sounds (other than being light on leg work!)?

Is it worth moving to free weights or do you get the same benefits from machines (I normally work out on my own so am slightly concerned about the weights without a spotter)?

The above takes about 25 mins - most other people seem to be there a lot longer - do I need to put more time or is it just that they like chatting?

[DazedandConfused]

Cheers for the advice - looks like I should be manning up and picking up the free weights with the bigger boys.

Out of interest why should you 'do your sets for each exercise and then move on to the next':

I currently do a 5 circuits (a la circuit training) - effectively meaning I have no rest before continuing exercise but 5 mins before the next set of the specific machine - this means I can be out of the gym super quick (~25 mins)!

If I did the same routine but focussed on each exercise separately (leaving a 2 min rest gap between each set as mentioned above) it would take approx 10 mins per exercise - almost 4 times as long in total ~80 mins.

Is this necessary? - not saying it isn't (I haven't got a clue) but it seems like a lot of sitting around listening to poor music when I'm supposed to be at work!