The card works fine, gave it a yank on each end of the cabling and it pulled out. I even managed to
get my files off the machine using the NIC (warning; some explicit language), even though that wasn't my original idea.
I'm not sure if the Dell Dimension 4500 supports Wake on LAN but I don't need it, so no point in looking it up [yet] because I wouldn't use it even if I could on that board.
I don't know if a transition is worth it or not but I hope so. The HP Vli8 has a 500Mhz Katmai and 384MB of PC100 shared with the onboard Matrox G220. While the Dell has a 2Ghz Pentium 4 (likely a Willamette core imho) and 256MB of PC2100. The brute force of the P4 alone should be helpful for my plans hehe, OpenBSD stable :-) instead of release.
My current plan?
Now that the OpenBSD install is transferred, use it's own case to construct PC #4 as soon as I can buy anohter power cord xD.