I'll let someone post who's actually got one, but there should be no problems with this setup at all.
A common mistake is to think that a PC has an IP address - it doesn't. The interface has an IP address, so each interface will have a different value.
As long as there are no identical IP addresses this should (conceptually) be fine.
If you are installing the PCI card, that means that you are using the HPNA networking stuff, not ethernet (not that this is important, just thought I'd mention it).
Hope this helps.
Paul.
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RioReceiver - Still Waiting for one in the UK.
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Paul Haigh, Reg. 4120
(mk1) 6GB, Blue, 00254
(mk2) 12GB, Red, 00357