Market Basket Analysis

Is there anyone who regularly does Market Basket Analysis / Frequent Item Sets, and can recommend any software to use (or not to use)? I am particulary interested in cost,ease of use,amount of data preprocessing required and how much data it can cope with. I have already tried Weka apriori algorithm and was wondering what else is out there.

Also, is there a 'common' format that shops store their sale data as. For example, I have shop ID and time stamps for each item and have to use these to determine which items are in the same basket (all items in a basket get the same time stamp). Is this 'the norm' (ie one item per row in the database and some common link)?

Thanks in advance for sharing your experience,

Phil