How would you want to see this info, or what is important?
Do you want to know which switch (3Com or Dlink), the port on that switch, the IP of the host, the name of the host (Netbios, or FQDN), MAC address, etc..
First, at a minimum each of the switches would have to be manageable. Meaning they would need to be able to support having an IP address, and probably SNMP polling so that you can login to the swtich and poll SNMP info.
If that was doable by each switch then some simple little scripts could be written to collect the rest of the info. You would likely have to create your own coorelation from MAC -> IP -> to hostname
There may also me some decent freeware products that can help with this, depending on the OS you are using.