Need help reformatting my Sony Vaio!

My pc is seriously messed up, I cant run Photoshop, Firefox stalls a lot, takes ages to respond or boot up so I want to format my pc. It has been slow for months. Here comes the problem....

I have a Sony Vaio and I have my recovery cd's. However, when I try to recover my system, I get the following message: Cannot use this recovery disk for this computer. Confirm model type.

For those wondering, I have no hardware or anything installed extra onto this pc. What am I doing wrong? How can I get around this problem?

Thanks for all help in advance.