Pavel Pogrebnyak's fifth-minute strike proved the difference, with the victory moving them to within five points of safety in the table.
The game may be quickly forgotten by many people but McDermott always felt it would be a big day for the club.
"I thought it was a really important game," he said. "I wouldn't have said that to anyone before the game but my gut feel was it was very important to get a result. We've got that. I might never look it but I'm very pleased. We had to be very resilient as we have done in the last three games.
"We want to attack and go for games but we've realised what we need to do to get results in this league."
The win followed a goalless draw at home to Swansea on Boxing Day and a 1-0 defeat at champions Manchester City three days before.
McDermott has said his side now understand the division more and the return to fitness of key players has allowed him to play the style of football he wants.
"We've missed Jem Karacan for a lot of the season and we couldn't play a certain way because we didn't have Danny Guthrie either," he said. "We were really struggling and Jimmy Kebe was also missing. We've had a real bit of bad luck.
"But what I like is that the fact that everyone - the 11 players, the subs, the entire squad - was in the dressing room after the game delighted. It's important for us, we've got everybody available again, it's been a good day for Reading Football Club."