date calculations using a time hierarchy

Hi There

I am a relative newbie at SSAS 2005, but I've created a working cube and populated it with data.

I have a fact table with three date fields:
[record date]
[start date] - date the product started
[end date] - date the product was withdrawn
+ some other data fields
I use the [record date] to analyse my data with a server-populated time dimension. So far so good, it works fine.
However I need to look at how many days the products were active during the current time period. For exampe, if I'm in Q1 of 2005 and my product ran from 1st december 2004 to 15th january 2005, the answer is 15 days. This needs to be totaled across various other dimensions too.
I have tried a lot of different ways of doing it without much success. Any ideas on how to implement something like this?

ThanksCould you explain the schema, and the granularity of the fact table - for example, is there only 1 record per product, or 1 record per sales transaction? In the latter case, shouldn't the product start and end dates be associated with a Product dimension, rather than with each transaction?|||It's a simplified proof-of-concept project, so I can understand how it works before trying it out on the full database which is more complex.
These are financial products which have a start and end date. There is one record per product and they are to be analysed by various dimensions, for example product type, which would be the maximum granularity (not the products themselves). I also need to look at them by other time dimensions, for example when the records appear in the database, which may be any time after they have actually incepted. So I could have product type on rows and time on columns, and the cells would be the sum of all the days of activity for a given product type for that time period. Or I could have 'appearence time' on rows, so each cell would be the sum of active days for products during the colum time, for all products appearing in a given time frame.
Hope this is clear enough? I realise this is maybe a bit general but I'm only after a general approach strategy rather than an in-depth analysis! Thanks
oh and Merry Christmas!