Mac browsing = bandwidth hog.

Why when I'm playing a game, I'll use Quake Live for an example, and another PC browses the net do I not get any change in my connection but the SECOND a mac starts browsing, reading email, loading ANYTHING web based, my connection goes to the proverbial?

I have tested this by opening the same email while playing Quake Live on both a PC and then a MAC. The PC and the mac were never on at the same time so it's not a simple matter of additive bandwidth usage.

The email in question was just some trash forward with cute pictures of animals.

To be more concise, the MAC seems to hog all my network resources doing the same mundane tasks that the other PC can do without affecting my play.

I'm seriously at a loss here, my connection is only 1500/250 dsl but this shouldn't be the issue as only the MAC is slowing it down.

It happened with the Wifes old desktop (iMac), her old mac laptop (Macbook), and her brand new laptop (MacBook Pro).

Any suggestions as it's really driving me up the wall, I just want a few good rounds of QL and the missus pops open the lid on that death machine to do some study and the connection just crashes to a halt.

Have you done any sort of traffic analysis to see what kinds of broadcasts the Mac is making?

I'd be willing to bet that the Mac has Bonjour and File Sharing turned on and is probably doing broadcasts during network access. I would check the Sharing applet in System Preferences and make sure everything is turned off and see if that makes a difference.