21.5 inch iMac as external display for HP Envy 17 Windows 7

Greetings, first post on the forum...just a simple technical question regarding the mini display port.

Basically i am in the market for an iMac base model 2.5ghz 21.5inch model which i would primarily be using for audio/video production and basic web browsing use, and very moderate gaming. I currently own a Win7 HP envy 17inch 3D model that has a Mini Display port. (link for specs HP ENVY 17-2002TX i7-2630QM 2GHz 8GB 2TB 17.3"W7HP [LN376PA] - $2,363.15) i use this as my university note taking laptop and powerhouse for gaming when at home.

What i would like to know is would i be able to link the Envy up to the Awesome/Crisp iMac display, and use this as an external monitor by just using the Mini Display port?. would i expect full 1920x1080 res and audio if i did so?.

If i plugged it straight in would it work, or would i need to change some settings in the iMac etc to allow this. i have also heard that the 27 inch model can be used as an external display, however not the 21...is this true?

Any assistance would be great!

Thanks.

The new Mid 2011 27" iMac requires Thunderbolt for input in order to be used as a display. (It has two Thunderbolt ports) The 21.5" model only has one Thunderbolt port. Your HP does not have a Thunderbolt output. However, the 2010 iMac 27" has two mini display ports of which one can be used for input. That model would be compatible with your HP.

As a side note here.... The Thunderbolt port is supposed to be backwards compatible with the mini display port, however, it remains to be seen if it would work that way for use as a monitor.