That's both the good news and the bad news. It means that useful information can be made instantly available worldwide. It also means that every crackpot can spew forth the most ridiculous garbage. Consequently, the WWW is rife with hoaxes and misinformation.
Here are several sites which may help. When you get something
that seems fishy, look here and see if it has been entered in these databases
of hoaxes and urban legends.
The San Fernando Valley Folklore
Society's Urban Legends Reference Pages
The AFU and Urban Legends Archive
Don't Spread That
Hoax!
HoakKill
Here I'd rather be safe than sorry. They may be hoaxes, they may not. But do check a warning before you send it on. Here is an excellent page maintained by our computer support folks in the School of Education.
Email
Virus Safety Precautions
And here's another useful page: