Yes you can use a flat screen monitor with any kind of desk top. You just simply hook up any flat screen monitor to you HP desktop and it should work fine.
To find out if you can use an LED flat screen with an HP Desktop computer, your best bet would be to take a look at the computer specifications, or contact HP directly.
well this equipment is greatly recommended for people who are the freaks of games, can be used to watch movies( but it'd be better if its of large resolution). :P:P:P