Personally, if I were a manager, I would rather like to simply click-n-drag the individual rows up and down. Somewhat like you can rearrange Firefox' tabs, only vertically. Having to enter numbers for this seems a little web-1.0-ish to me.
Unfortunately, the already mentioned jQuery datatables plugin doesn't provide that functionality, AFAICT (I'd like to be proven wrong) - although it's an otherwise very neat widget. So, if anyone is aware of some other js library which can do it, please tell...