PS3 not connecting to Orange Livebox - why?

Hi all, I am not the most 'techie' of people and need your help.>>

I have had a PS3 for a while now, it's the old 80gig version. Fr some reason I have never been able to use it wirelessly with my Orange Livebox ever since I have had it.>>

Do I need to buy a wireless router for the PS3? It is wireless isn't it? (told you not the most techie)>>

The PS3 does find the Livebox but always comes up with a DNS error message. If it makes life easier I will just buy a router and connect it to the PS3. I have even positioned the livebox next to the PS3 to rule out any signal issues.>>

If you know what the problem could be OR know of a simple solution then please let me know.>>

Thanks in advance.>>