globalsi
Whatever version of sme7.x you have, you should upgrade it to sme 7.6 first before doing any upgrade (even to sme 8.0), as there were important package upgrades in sme 7.6 that allowed smooth upgrade to sme 8.x etc.
The only practical way to upgrade to sme 7.6 now, is to download the iso from an archive mirror site, burn a CD & run the upgrade from CD.
If already at sme7.6 then should be OK to upgrade via backup & restore.