Giuffria is originally from Gulfport, Mississippi, graduating from high school in 1969. A talented keyboardist, he moved to the US West Coast where in the late 1970s he joined Angel. After the band broke up in 1981 Giuffria put together his own band, Giuffria, with vocalist David Glen Eisley, guitarist Craig Goldy, bassist Chuck Wright, and drummer Alan Krigger, and achieved some success with their first eponymous album and first single "Call To The Heart," which made the Top 20 on the Billboard Hot 100. The band broke up after the commercial failure of their next album Silk and Steel" in 1986.
Giuffria then put together the House of Lords with the help of Kiss' Gene Simmons and signed to Simmons' label. The first album House of Lords, was released in 1988 and experienced a modest amount of commercial success with the single "I Wanna Be Loved". However, this success was not consolidated as the band were unwilling to tour.
However, Simmons decided there was enough potential to warrant the release of a second album, and in 1990 the band released Sahara. The album reached #120 on the Biilboard charts and in the wake of the successful single "Can't Find My Way Home" (a Blind Faith cover) was certified platinum in 1991.
A final album Demons Down, was released for the Japanese market in 1992. The band broke up in 1993. House of Lords has since reunited, but without Giuffria, although he does appear on their 2006 release World Upside Down as a guest keyboardist. Gregg worked on a solo album with an expected release in 2006, but as Hurricane Katrina wiped out his business ventures in Biloxi, it is uncertain when the solo project will ever be released.
Gregg was also the CEO of the Las Vegas based Outland Development LLC, that designed and built gaming machines and theme park attractions, and was president of casino operator Full House Resorts from 1998 to 2000. He is also co-owner of the Biloxi Hard Rock Hotel and Casino, along with partners Roy Anderson III and David Ross. Gregg now lives in California.