wm6.5 to 8.0

Hi all,
As we are using IS 6.5 sp 2 and TN 6.5, and we gone through the upgrade document and it recommends that we have to upgrade from SP3 to 8.0.
Do we do upgrade directly from SP2 to 8.0 as we are not using any web services in my application? Otherwise can we use service pack 3 to upgrade IS ?(as we are assuming that we can install only SP3 to upgrade) So that we can upgrade to 8.0

If you say that we have to upgrade from sp3 only then, what will be procedure to upgrade from SP2 to SP3 and where will we get SP3 pack and how to do that? then sp3 to 8 ?

Pls let me know details !