This is where the Jehovah's Witnesses really fall down on their theology. According to their own eschatological views, there are two resurrections. The "heavenly class" are resurrected as spirits, while the "earthly class" are resurrected as physical beings, like Adam and Eve were before the Fall. Forget that there's no indication of this in scripture or tradition at all. That's the way it is.
Anciently, the holy ones taken into temple service were all "virgins" in the sense that they were temporarily celibate. In a metaphorical sense, the 144,000 are virgins in the sense that they will be free from the influences of the world. While the Antichrist will have the mark of the Beast on their foreheads, the 144,000 will have the mark of the Father in their foreheads.
Rather than argue what the 144,000 are, it's easy enough to determine what they are not, and it's clear that some deliberate monkeying around with the scriptural exegesis has been done by the Watchtower crowd.
All resurrections will be as Christ's resurrection. That means a physical resurrection of flesh and bone (not blood). The Watchtower theologians, when pressed, will ask that one disprove their interpretations when, in reality, it is they who must prove theirs. Much has beeen written about the 144,000 and their roles in the last days, but we know from scripture that through Christ, all men, good and evil, will be resurrected. Not as spirits, but as physical beings.