so i found this cute theme from some site, but the theme is only offered for OS 4.2, and my OS is 4.5, if i were to use the theme, would it kill my bb?
No. Using it will be fine. You can't use themes designed for a higher OS (for example, one designed for 4.5 if you're running 4.2), but in your case, you're trying to use one for a lower OS, so you shouldn't have any issues.
Posted from my CrackBerry at wapforums.crackberry.com
Actually, there wouldn't be any issues other than the fact that the theme won't work at all! You need to match the themes OS to your phones OS in order for them to work!
Posted from my CrackBerry at wapforums.crackberry.com