I use the Quirky Update method and will probably continue to do so even after my company upgrades to 2012 and then to 2014. It's not for the faint of heart and there are a shedload of rules to follow but, for the size of the tables I used it for, it was worth it. It'll do a running total on a million row table (comparatively small nowadays) in just a couple of seconds even if you use the more complicated version with built in "sort order verification".

As an alternative, if the table that you need running totals for is a WORM table (write once, read many... like a check book where corrections are added in as additional transactions) AND you don't mind storing the running total, it might be better to use a trigger or some other code to calculate the running totals just for the new rows based on the previous maximum record.