Hello Roger,
If you are already familiar with using LabVIEW to control this instrument from a GPIB controller in your computer, then switching to a GPIB-ENET box should be relatively painless. All LabVIEW needs to know is which GPIB controller to use.
When you install a GPIB board in your computer, it usually defaults to GPIB0 as the interface name. So, if you still have a GPIB board in your computer, it is probably using GPIB0 as the interface name. This is transparent to you with LabVIEW, because LabVIEW defaults to using GPIB0 for its GPIB communications.
You left out a key part of the problem here, namely: which operating system are you using?
If you have a Windows 9x operating system, then you can leave your current GPIB board in your computer and "add" a GPIB-ENET to your system. If you already have a GPIB board installed as GPIB0, then the GPIB-ENET will default to the next available interface name, which is GPIB1. This might cause some problems with your LabVIEW program, because you would have to tell it to use GPIB1, instead of GPIB0, if you want to use the GPIB-ENET to control the instrument. However, you could simply swap interface names, so that the GPIB-ENET would use GPIB0 and your "in the computer" GPIB board would use GPIB1 instead. This is easy to do. See the Tips on Setting GPIB Properties page in the GPIB Support section of the National Instruments Technical Support site (http://www.ni.com/support/). You can get to this page through the GPIB Installation Wizard (http://www.ni.com/support/gpib), but here's a direct link to save you some time:
http://www.ni.com/support/gpib/max/property.htm
If you have Windows NT/2000, then you will need to uninstall your current GPIB driver and install the GPIB-ENET driver instead. If you do not have a copy of this driver, then you can download it through the National Instruments GPIB Support page (go the http://www.ni.com/support and select GPIB as the product line to get there). Once you install the driver and configure your GPIB-ENET, it will probably default to using GPIB0 as its interface name. If it doesn't, then you can change its name to GPIB0, so that LabVIEW will work through the GPIB-ENET to control your instrument.
I know I've written a book here, but to recap: configure your GPIB-ENET for use with your system, and make sure that you're using GPIB0 as the interface name. You shouldn't have to change your LabVIEW code at all. (Check out that GPIB Installation Wizard link that I gave earlier, if you have questions about installing your GPIB-ENET.)
Best of Luck,
Dieter
Dieter Schweiss
Applications Engineer
National Instruments