Although the VietNam war was not strictly part of what is considered the 'Cold War', as Imalko stated the involvement, directly and inderectly, of the USA and the Soviet Union, had a bearing on the global situation regarding any potential confrontation between NATO and the (former) USSR.
Personally, I would prefer, for the purposes of the GB's, to see Viet Nam, and Korea, covered by separate Group Builds, as I see the 'Cold War' as strictly a potential conflict between NATO (and the 'West' in general) and the USSR and her WARPAC allies, which, as we know, came very close on more than one occassion.
However, in the case of the Yom Kippur war, that was definitely a crucial point in the 'Cold War', aswith the support to both 'sides' from the West and the USSR, it was though that it might be the final turn of the key which could have initiated full-scale war between the USSR and the West. At the time, Soviet forces were mobilised in northern Europe, and moved to within metres of the Finnish border (some actually crossed), and NATO forces in Germany were put on immediate stand-by (I was there!).
Other conflicts that might have 'upset' either the 'West' or the USSR, such as Angola, Erirtria, Somalia, Grenada etc etc were just that - conflicts, which, although perhaps sensitive in as much as they affected East - West diplomatic relationships one way or another, were not on a scale that could have lead to intervention, leading to possible/probable escalation, by one of the so-called 'Super Powers'.
But in general Neil, yes, you are right, the 'Cold War' is normally seen as the uneasy peace between the 'West', and particularly NATO, and the former USSR.