RSView & S7400

I have an RSView data collection app running and I would like to capture data from a Siemens PLC and/or HMI via ethernet link. What are my options?

You can use a third party OPC server for the PLC (I still recommend Topserver http://www.toolboxopc.com/ ).

You can use the Simatic Net OPC tools as well.

If you want to use the software from Siemens, then I recommend that you check out the guide that I wrote. It can take some time to figure out by oneself.
SIMATIC NET OPC For Dummies (open with read-only).

There are a number of pitfalls depending on the kind of connection and hardware you will be using.
What network type ?
What PC hardware will you use ?

Oh, I see that you stated Ethernet in the original post.

Then I recommend Simatic Softnet Ethernet Lean (Siemens part no 6GK1704-1LW63-3AA0) - it is quite inexpensive.
It will work with the onboard ethernet NIC in the PC. No need to purchase a special Siemens ethernet card.
You will have to adapt the example in the guide to ethernet. The guide is made for MPI or Profibus (maybe I should take some time to update the guide with ethernet, hmmm...).
The PC and S7 have to share the same subnet (i.e. IP addresses 192.068.0.1 and 192.068.0.2) in order to "see" each other.