I had a dell with one of those straight leads. After a couple of years it started shorting out and I had to buy a no-name replacement on ebay.
The socket itself also started to wear, it would only charge when the plug was firmly in and it would fall out frequently, meaning you could only use the laptop on a table.
Have a Packard Bell now and it has a 90 degree plug and its much more secure.
Run it off the battery and then charge as needed?
All my laptops have had useless battery life after 18 months, and thats with the laptop power being off overnight, so in the morning the laptop uses the battery until it reminds you to plug in. So inevitably the laptop will still need to be charged whilst in use.