Different OSs, different experiences?

Is there an obvious reason why my editing experience at home should be slower than the same experience in the office? Superficially at least, everything seems similar – same site (obv.), similar connection speeds (8-11MB), both machines with proprietary (Windows) firewalls and similar routers … the only difference is WinXP at the office and Win 7 at home. Is it the operating systems? All help, as ever, appreciated …
<toyah>It’s a mystery</toyah>
The internet load speeds for pages when NOT editing are similar too …