5-min. video on web-site-how to format?

I have loaded a 5 minute video out to the web site for a local not-for-profit … it is 90 meg. When I invoke the video – it takes about 10 minutes to load down (cable modem) and then Windows Media Player takes off – and it looks good. BUT – this 10 minute delay is too long to ask a user to endure … and with a regular modem – it would be far, far too long to load.
What format should I convert the 90-meg .mpg file to – or what should I do to convert the
.mpg file … Thanks for your help…