Every now and again my laptop will disconnect from my router, and was wondering what the problem was. The laptop isn't...

The battery life of the laptop is somewhere between 1.5 and 6 hours, depending on the use scenario. If you're getting near or below the low end, the battery might be nearing the end of its lifetime. You could get a 9-cell battery, which is heavier but offers better battery life. Keeping batteries from older systems plugged in can cause them to degrade faster. It might be a hassle, but you can extend an old battery's lifetime by keeping the battery out of your system when you plan to have it plugged in for a long time.