Should I use a higher sampling rate when encoding songs in iTunes?

I recently picked up a 250G external HD to use as backup and to store my itunes. Very happy. Now I’m wondering if I should start using the 256KB sampling rate (higher quality) v/s the 128K (high quality) that I’ve been using. It seems that disk space won’t be a problem for a while (wait! when does that Terrabyte drive go on sale?) although it take a little longer to rip or copy. I’m currently only using my iPod with regular earbuds, so I don’t think I can hear a difference. Do you think the higher sampling rate will be noticeable with better ‘phones or when I burn CD’s?