Nektar is a great band with an excellent guitarist in Roye Albrighton. The first six albums from the original lineup are all very good:
1971 Journey to the Centre of the Eye
1972 A Tab in the Ocean
1973 ...Sounds Like This
1973 Remember the Future
1974 Down to Earth
1975 Recycled
Roye Albrighton left the band to form his own group and the subsequent album, with Dave Nelson and Larry Fast, is in a slightly different style but is still a strong album (ignore the critics):
1977 Magic is a Child
The band recorded two albums live in New York. Both are good, but I cannot track down the second on CD. The NearFest album may be an offical bootleg and again, is excellent, but seemingly impossible to find:
1977 Live in New York
1978 More Live Nektar in New York
2002 Unidentified Flying Abstract - Live at Chipping Norton 1974
2002 Nearfest 2002 (Studio M Recording)
I do not know much about these later albums:
1980 Man in the Moon
2001 The Prodigal Son
2004 Evolution
2008 Book of Days
2011 Juggernaut
When the 'classic' Nektar lineup reformed in 2002, Larry Fast also rejoined the band. The Nektar project site says Dave Nelson went on to some solo work and joined a band called Spy, before going into finance. I have not heard his solo work or his work with Spy. Roye Albrighton formed his own band, following the split with Nektar, and the musicians seem to have disappeared.
An interesting little ditty: Roye Albrighton played the nifty guitar parts on the excellent Lone Ranger single by Quantum Jump.