The last time the Royals won 6-0 was a thrashing of Preston in February 1990 when Reading were a Third Division outfit.
They have come a long way since then, while West Ham's fall from grace was starkly illuminated by this Premiership humiliation.
Reading's first win in a month was never in doubt and left Curbishley in no doubt as to the size of his rebuilding task in 2007.
Reading were in control from the first whistle and served notice of intent with two early Steve Sidwell chances, a flicked header over the bar and a dipping volley straight into the arms of Robert Green after Hammers had only half cleared Nicky Shorey's free-kick.
But it was West Ham who nearly took the lead on eight minutes when Yossi Benayoun played a clever ball behind Ibrahima Sonko for Lee Bowyer to run on to. But the midfielder couldn't get enough on his shot and presented Marcus Hahnemann with an easy save.
But, four minutes later, West Ham's game started to come apart at the seams as Reading opened the floodgates.
Danny Gabbidon again conceded a free-kick wide on Reading's right flank and Shorey once again produced a precise delivery for full-back Brynjar Gunnarsson to charge on to and flick a header past Green for his first Premiership goal.
Two minutes later, Stephen Hunt was also celebrating breaking his Premiership duck after another incisive move down Reading's right.
Glen Little dropped a clever ball in behind Paul Konchesky for Sidwell to run into space and hook a cross to the far post, where Hunt arrived unmarked to steer a free header back across Green and i to the far corner.
West Ham's miserable afternoon took another nasty twist on 19 minutes when Bowyer fell awkwardly under a challenge from James Harper and was forced off with an apparent shoulder injury.
His replacement was Shaun Newton, making his first appearance following a seven-month drugs ban.
But Curbishley's misery was far from complete as Reading continued to pile forward in search of more goals.
Kevin Doyle fired a low shot into the sidenetting after being allowed to run in to acres of space, before the home side extended their lead before half an hour showed on the clock.
Gabbidon again conceded a free-kick in an almost identical position to his earlier misdemeanour and Reading were once again ruthless with their punishment.
Again it was a delicious free-kick from Shorey which caused panic in the West Ham defence, but this time it was Anton Ferdinand who headed into his own net under pressure from Sonko.
The hapless goal summed up West Ham's miserable start to the game and prompted ironic chants of "Pardew in" from the Reading fans, referring to their former manager who was recently sacked by West Ham's new owners.
The impressive Little threatened another but saw Gabbidon hack clear from his sidefoot effort, but the home side did add a fourth nine minutes before half-time.
Shorey was again the creator, setting off on a mazy run and setting up Harper for a clever low cross that was turned in at the far post by Doyle.
The fourth goal even produced a rare smile from Reading boss Steve Coppell, caught on camera in the directors' box. But for new Hammers' boss Curbishley, the only look was one of utter bewilderment.
Curbishley gave Gabbidon a touchline dressing down as the teams came off at half-time and made inevitable tactical changes during the break.
Curiously, it was striker Marlon Harewood who came off and defender Jonathan Spector who replaced him. But if the switch was designed to stem the flow of goals, it didn't work.
Eight minutes into the second half, Reading raced down the right again as Doyle spun and played in Sidwell and his low centre was bundled home by Leroy Lita despite the efforts of Green.
Green was beaten again 14 minutes from time when another Shorey set-piece, this time a right-wing corner, was headed home by Doyle.