Nickel based tehcnologies prefer to be fully discharged most of the time. However, in a modern laptop the battery will be lithium based. Assuming it is lithium technology (lithium ion or lithium polymer) then it is actually best *not* to fully deplete the battery. They last longer at under 80% depth of discharge (i.e. at least 20% remaining when you charge it). Although, some manufacturers appear to leave a little reserve to prevent deep discharges, so it is hard to tell (my Dell batteries discharge to 10.5V rather than the expected 9V which means it does the batteries less harm to deplete them fully in the laptop). The basic rule is charge lithium batteries little and often. However, recalibration of the fuel guage is required after about once a month, which requires running the battery to empty and then doing a full charge. However, it is best not to do this every time you use the battery.
Although, here comes the caveat. Lithium batteries don't really like being in a fully charged state for too long, so leaving them fully charged degrades their capacity over time, particularly when kept warm rather than cool. This means that a working laptop is the worst possible place for a lithium battery, since internal temperatures are high and the battery is kept fully charged. If you do a lot of work on the mains, or worse play games, you can always remove the battery completely whist working on the mains and keep it somewhere cool (not the fridge though, they don't like condensation!).
As for storage for extended periods (not sure a week is that long though), it is best to leave them partially charged (40% is quoted by the battery manufacturers) to account for some self-discharge. This reduces by quite a lot the capacity decrease suffered by long term storage (particularly at 100% charge). Dell, for example, recommends charging to about 80%. It is the top part of the charge that seems to do the damage. *Never* store them completely empty, as self-discharge can take the voltage critically low and cause the protection circuit to trip, meaning that the battery is then unusable.
To be quite honest though, lithium batteries die naturally from the day they were made. 3 years is the normal life in very good conditions (like mobile phones, where they are never stored for long at 100% and are charged often). 1 year is normal for a laptop where they are kept warm/hot at full charge for extended periods.
Hope this helps,
Martin
