I think you'll only be able to open them if you have Quicken installed? - Does it give a .csv (comma seperated values) option? Certainly Lloyds bank does and that is how I get mine (which then open with Excel).
I have used Quicken for years now and downloaded Natwest and MBNA statements online also for years. If my wife is out shopping and spends any money on a card it is live on line and can be read almost at once, in other words it is not only the monthly statement but hour by hour entries. I have recently changed to Microsoft Money which does the same thing, just fancied a change, it converts Quicken files to Money and saves a Quicken backup. Friends have used both Quicken and Money with other banks and never mentioned problems. The only problem I ever had was when I installed Firefox which refused to download MBNA so I went back to Internet Explorer. Ruskle.