So what I might need to do is create a spreadsheet that does the following:

1) The user enters input values and expected results
2) Creates an XML document from the input values
3) Sends this to a web service and gets results back
4) Compares the results to the expected results in the sheet

Sound possible? I've not got much experience writing this kind of Excel stuff….

It's for a testing framework.

why not just create a simple test app? .net/Java/?
.net and Eclipse can auto generate a lot of your test case stuff from a wsdl

1) easy either via a user form or into the worksheets,
2) shouldn't be an issue
3) possible but not sure how, i have used google analytic plugins so i know it can be done.
4)once you have the numbers easy.

i guess define some variables in the VBA and if a=b then "" else ""

Sounds like stuff I used to do on occassion.

Back then used to use Perl (since I don't know VB) to:
1. parse a plain text input file (in your case, if input has to be Excel, I'd have tried to use something like the Spreadsheet::ParseExcel module)
2. convert to a SOAP XML query using the SOAP::Lite module
3. send query to remote server (still SOAP::Lite)
4. receive SOAP response with result (still SOAP::Lite)
5. parse response (still SOAP::Lite)
6. write output to plain text (again, if out has to be Excel, perhaps Spreadsheet::WriteExcel would do the job?)

But I'm willing to jump through hoops to use a language I know (and VB I don't). If you know Perl though, SOAP::Lite is super easy to work with…

I agre would be easier in something other than VB I have done something similar in Python.

Excel is a requirement.

Believe me if I could avoid VB I would.

Yeah.. thanks for telling me to do it in other languages!

It's not the doing of the things that's the problem, it's the doing of them in Excel

does this help, excel export to xml

and this soap for excel.