newbie: what's the most convenient and safest way to update from FC3 to FC6 or further?

[LIN QIU]

hi,

I am a newbie to linux, had used Fedore3 for one month,
since it is not supported now and many softwares I am trying to download
are for higher Fedore version.

Is there some convenient and safe way to update to FC6 or FC7 without
compromising my current working environment much? (I mean like just
update the kernel)

LIN