For removing labels and their adhesive gum, I use lighter fluid (the kind
made for old cigarette lighters) to remove labels. Zippo and Ronson are two
major brands. You can buy it at almost any grocery or drug store (it may be
behind the counter, ask). It's very effective and doesn't seem to leave a
residue or cause long-term plastic damage. I also use it for cleaning old
laptops, put some on a paper towel and it works great, it's just a good
solvent. [Do not use it on the screen ... I will use Windex on an LCD
screen, however. It's harsh and frequent use is definitely not recommended,
but very occasionally, it's ok and works very well.]