which open source business intelligence solution would you recommend?

All I need is to build some cubes and let the end user play with dimensions, filter data, sort, etc, and once it's done being able to export it to excel...

I'd like the solution to be as simple and easy on resources as possible, and also I'd like it to be as much open source as possible, by the way. I've heard that many solutions available do have many restrictions when it comes to there community version.

I'd like to ear your advices and the pros/cons of each alternative, to help me choose the right tool, and if you could point me to some basic demo and tutorial to get started.

thanks a lot

ps: I'm using sql server databases, they aren't huge databases (in general less than a million records) and I doesn't necessarily have to work on "live" data...

ps: some useful links:

http://en.wikipedia.org/wiki/Business_intelligence_tools#Open_source_free_products

http://www.manageability.org/blog/stuff/open-source-java-business-intelligence

http://www.jaspersoft.com/jasperanalysis

http://community.pentaho.com/projects/bi_platform/ http://community.pentaho.com/faq/platform_licensing.php

http://www.eclipse.org/birt/phoenix/

http://www.spagoworld.org/xwiki/bin/view/SpagoWorld/

http://docs.google.com/viewer?a=v&q=cache:vhsqMQXwCUkJ:www.ow2.org/xwiki/bin/download/Activities/EuropeLocalChapterWebinars/ELCWebinarOSBI.pdf+open+source+business+intelligence&hl=en&pid=bl&srcid=ADGEESgpJJ2MqaKprJQOF2jX2UXCZQjg_asv8d7EVYtq0Vma-e-tR1tFxS-I0SOW0IhJC5acYc94rkDOrgP1WckCp_vk4qhKqR9y2Klp_u9cL8hlXoKoUpMkpAd5wabu61A4W0y15E5P&sig=AHIEtbRJ5FAI-3YK-qtayPjKkF_CwOgZag