Peter:
In general it is not a super idea to use an N-Channel FET by itself to drive a relay when the microcontroller is of the 8051 variety. If you look at the circuit that I posted here http://www.8052.com/forum/read.phtml?id=64176 some time ago (and referenced again by Raghunathan) the idea behind the dual stage driver is the elimination of the power on activation of the relay.

With a relay driven exclusively by one of the N-FETs that you recommend there will be a moment between power-on and when the 8051 can get around to driving the port pin to a low level to turn off the 2N7000. This brief period can cause the relay to click or to turn on momentarily.

I'll grant you that there may be some designs where having the relay coil be active directly from power-up time may be the desired logic configuration. On the other hand this is NOT how I like to design relay and output circuits on the 8051. I like to have the software in the microcontroller be able to take the actions of when it is appropriate to activate outputs and turn on the relay. For this reason it is needed to use the port pins in an active low mode to drive the transistors that in turn drive the relay.

So I would recommend to go ahead and use the 2N7000....but either use two of them OR mate one up with an appropriate P-FET type device so as to realize the equivalent circuit topology as shown in the circuit.

Michael Karas