From thinkbroadband and confirmed on the o2 website
To date the various mobile and land-line broadband bundles have only applied to customers with relatively expensive monthly contracts. O2 Broadband is to extend its £5 discount to all its pre-pay (pay as you go) customers who top up their mobile with £10 every three months. The discount will be available from Friday 22nd February 2008.
Pre-pay customers taking advantage of the offer will need to agree to a 12 month contract on the broadband service and the discount is automatically taken off the 02 broadband bill so long as they keep meeting the £10 every three months top up rule. If the £10 rule is not met then they will be charged the non-discounted price for the broadband service on that particular bill.
Three broadband packages are available from O2, Standard at £7.50 for an up to 8Mbps connection, Premium for £10 per month with up to 16Mbps connection speeds and finally Ultimate with an up to 20Mbps connection for £15 a month. Standard and Premium offer an upstream speed of up to 1.3Mbps, Ultimate increases the upload speed to 1.6Mbps. The non-discounted prices work out at £5 a month more. There is no defined usage limit, but a fair use policy applies to all three products.
The services are only available where O2 has installed its own hardware at the local telephone exchange (commonly known as unbundling an exchange). The O2 checker will allow you to see if it is available in your area.
I'de be looking at this lot if I didn't get free ADSL from my employer.