Right from the metronomy web site:
Terms and Conditions:
1) On screen advertising: In exchange for your free PC, you must accept up to 3 minutes of on-screen advertising per hour of PC use. Every month, you will receive a cd containing adverts to be shown over the following four weeks. Each disc must be loaded onto your PC for the system to update. Should you fail to do this, your PC will be disabled.
2) The PC is lent to you for a term of 36 months, after which you will be offered a new computer and a new agreement, or you can simply return the old machine to a local collection point.
3) Your household must use the PC for at least 30hrs per calender month, or approximately 1 hour a day.
4) The PC must be connected to the internet at least once a month, and you must maintain an ISP (Broadband, 56k or ISDN) account throughout the term of the agreement.
5) The principle applicant should be 18 or over, and provide a home telephone number. We will conduct a security check linking you to the address given. Under certain circumstances, you may be requested to provide alternative proof of ID. This offer is restricted to one PC per household, and is only available to UK residents at this time.
If you accept these terms and conditions and consider yourself eligible, then please click on the 'Order your free PC' button to the left of your screen, and complete the short application form.
Computer:
Intel Celeron 2.4ghz
256Mb RAM
40Gb Hard Drive
Intel Extreme 64Mb onboard Graphics
DVD Rom
56K modem
Integrated Audio
Infinity Ext Speakers
Microsoft XP Home pre-installed
IBM E54 15" CRT Monitor
Includes Full 3 year IBM warranty
Q: What happens when the advert is served? Do you lose what was on your screen? For instance, what would happen if you were playing a game or in the middle of an online shopping transaction?
A: 60 seconds prior to advertisements being shown, a warning screen will appear, the screen contains an accept and delay button. Each advert broadcast can be delayed for 5 minutes to enable the customers to either pause a game or complete on-line transactions.
Very interesting.
AO
keep the computer in the corner but swap out the processor for a 486 or something and replace the HDD with like a 1 gig one and take all the good stuff and put it on your PC, as long as it is running and displaying adverts, the monitor doesn't even have to be attached they have no way of knowing then you got free parts 
