Cat5, 5e or STP?

Hi All,

I've been aked by a mate to help him run some extra network and
digi-voice points to an office at the end of a building.

Some of the existing cables are straight Cat5 and some seem to be the
shielded version? I'm not sure how they have previously dealt with the
screen on the STP run and I doubt any of the leads frm the wall boxes
to the PC's are STP (if that matters?). Some of the runs are bound to
go near mains cables and look about 50m

Before we order the cable in there anything we should consider please?

PS I *have* run / terminated and made straight / x-over Cat5 patches
before, it's just the UTP / STP and Cat5 or Cat5e bit's I'm not sure
about?

All the best ..

T i m

p.s. I flood wired my house with Cat3 6+ years ago .. ;-)