Assuming you don't want to leave your PC on while you're on holiday, the only way it can work is to have the mail server (e.g. Exchange) respond for you.
Check with your ISP/domain/e-mail provider as quite a few offer auto-responder facilities which can be used for this purpose.
In theory, you could leave your PC on with Outlook running and allow it to connect to the internet and collect and process mail every so often. You could then use Outlook rules rather than the 'out of office' Exchange feature. This could be particularly risky if you're on dial-up where you have to pay for the calls (if it doesn't hang up properly for instance!).
Or, you could always run your own mail server...
