Windsor have recorded a seventh win in a row in all competitions and reached the Berks & Bucks quarter-finals after victory at Stag Meadow.
The deadlock was broken after 13 minutes and a goal that owed much to the quick-thinking of ex-pro Harry Hayles - who is the subject of a Soccer AM camera crew tonight.
Windsor appealed for handball but Hayles carried on and drove into the box, crossing low with his left foot for Nadir Shafi to convert from close range.
The second goal in the second round tie came just five minutes later and was more of a gift from the Newport Pagnell defence.
Shafi worked hard to force an misplaced pass and the loose ball fell invitingly for Denton. His first shot was saved by keeper Mark Osbourne but the former Reading player made no mistake with his second effort, firing into the unguarded net from just inside the box.
Windsor did not have it all their own way though and keeper Henry Poole had to make at least two smart stops to maintain the lead at Stag Meadow.
Chances for both sides were few and far between after the break but Windsor came closest to scoring when Denton hit the crossbar with a free-kick 20-yards from goal.
1) Henry Poole
2) Ashley Smith
3) Haydon Clack
4) Luke Brooks-Smith
5) Andrew Ingram
6) Joash Nembhard
7) Paul Coyne
8) George Gould
9) Nadir Shafi
10) Barry Hayles
11) Jack Denton