codedipper,
From your description, I visualize two possible scenarios:
1) that your Sheet1 is being used as an Input sheet, and you want to transfer the data from A1,B1,C1 to either Sheet2 or Sheet3, based on the value entered in D1.
2) that your Sheet1 is a "database" with a large number of records, and you want to selectively extract records (based on each record in column D containing either an "a" or a "b"

to either Sheet2 or Sheet3.
In BOTH cases, it's possible to have VBA code (attached to a button) that would perform either task.
A preferable approach to coming up with an accurate solution would be for you to email a copy of your file. A solution could then be provided and the file emailed back.
If you'd like to email me a copy (with confirmation as to your objectives), I'll help in providing a solution. If you happen to have sensitive data, replace it with fictitious data that still reflects the type of data you're working with.
Regards, ...Dale Watson dwatson@bsi.gov.mb.ca