Wel, it seems I've found a solution for my Redhat-in-a-VMware network problem. What's causing this is still unclear, but I now have a workaround. The problem was that Redhat (RHEL4) and Fedora (Core 8) had a lot of trouble in obtaining an IP address in a VMware cage. Other operating systems like Solaris 10 or CentOS5.1 worked like a charm. After meticulously comparing the settings in CentOS and RHEL, networking still refused to work, so I decided to give up (thinking this might be a RHEL/VMware combination issue) and resorted to QEmu.
But Qemu has its world of problems on its own. Kqemu wasn't supported on my laptops CPU, which meant a fairly low performance, but in the end I could live with that. You can download torrents for preinstalled Qemu OS images on FreeOSZoo, but that won't guarantee that anyone is seeding the image of your choice, of course. I opted for a OpenSuse guest, which after a long install, also had troubles getting on the network. But that one bound itself to another network class address than my wireless connection.
A then I bumped into the solution : on my laptop, eth0 is bound to the wired Realtek ethernet controller, whereas eth1 is bound to my wireless connection. As I use wireless exclusively, eth0 never gets attributed an IP address. It seems that on the problem images in VMware, eth0 is bound to eth0 on the host, and if that one doesn't get an IP address, you're lost too in your VMware guest. I tested this immediately, and connected my laptop to a good old utp connection, and fired up the RHEL4 guest. And bingo, IP address obtained !
This doesn't off course explain why CentOS or Solaris do get an IP address. Maybe NetworkManager or avahi-daemon are configured differently on CentOS (and are absent on Solaris), but the fact remains you better attribute an eth0 address on the host if your VMware guests want to be connectable.