Hey Leo,
As an FYI, InfoPath now has SP2 out and you might find it beneficial to install this. A link to the downloader is on the left side of this page.
How many rows are you dealing with in this report? If you are only dealing with a small amount or are pulling the information over a LAN connection, you can use a quick-and-easy data filter in InfoPath to filter the results once you have pulled them all down. This process is explained at the bottom of this HowTo:
http://infopathdev.com/howto/tutorials/default.aspx?i=3ed83f87f32a4b9699dfcd232cc4e602 - You will need to do a little bit of tweaking it get it to work with your schema, but it should be pretty straightforward.
If you want to get down-n-dirty with the query, you could construct a CAML query to filter the results before SharePoint returns them, and therefore achieve a decent performance update. This is quite a bit of work, but it might be necessary in your situation. A rather complex example is given in this HowTo - it shows how to setup a CAML query to write to SharePoint, but the same can be done to retrieve information. If you would like more specific advice, let us know!
http://infopathdev.com/howto/tutorials/default.aspx?i=7bc880f391b84ea9b3b45c6fbecc07c6
Matt Faus / Microsoft InfoPath MVPQdabra® Software / Streamline data gathering to turn process into knowledge