just look at the oracle text of the card. It doesn't say "your" anywhere in there. All creatures and all lands get untapped, even ones that aren't yours
Use that link to look up cards. All cards are treated as though they have their Oracle text printed on them, and the Oracle text is up-to-date, so you don't have to worry about 'old card wording'.
Just a quick question on the wording as its an old card. Does it mean all lands and creatures in the game or just your own?
Ex-DCI Level 1 judge
Ex-Rules Advisor
http://gatherer.wizards.com/Pages/Default.aspx
Use that link to look up cards. All cards are treated as though they have their Oracle text printed on them, and the Oracle text is up-to-date, so you don't have to worry about 'old card wording'.
The latest Comprehensive Rules are also good, and can be found here.