My choices are (some are on youtube, some aren't) :
Strawberry switchblade - Sunday morning (original by Velvet Underground)
Thumpermonkey lives - Tam Lin (a traditional murder ballad, so there is no definitive original version, but this one is based on Fairport Convention's reading)
The Stranglers - Walk on by (originally recorded by Dionne Warwick)
Mike Oldfield - Platinum IV (original by Philip Glass as "North Star")
Tangerine Dream - Love on a real train from the "Risky Business" OST (original is section VII of Music for 18 musicians by Steve Reich)