Despite the final scoreline, the match was competitive in the first half as both sides battled to cope with the wet and windy conditions at Home Park.
Windsor took the game to their opponents first and were 6-0 ahead after 10 minutes thanks to two penalties from James Driscoll, punishing Slough twice for being caught offside at the breakdown.
Slough had the opportunity to put points on the board, but failed with two penalty kicks of their own.
It was the away side that began to find momentum, though, as Windsor were missing tackles and their defensive kicking was failing to find touch.
And Slough took advantage to score the first try of the game and take a 7-6 advantage.
Windsor hit back with an unconverted score from Pat Birch but Slough dominated the remainder of the half and went in at the break just a single point down after a fine drop goal.
The half-time team-talk must have galvanised the hosts as they came out strongly after the break and scored their second try through Birch.
Driscoll was unlucky with his conversion as it hit the bar and Windsor were then reduced to 14 men when Michael Curtiss interfered with the ball while offside.
But the hosts scored again when Tom Strauss powered to the line and Driscoll kicked the easy conversion from in front of the posts.
Slough kept themselves in the match at 23-13 with a penalty only for Windsor winger Jono Sandilands to jink past the defence and score in the corner.
Despite the driving rain, the hosts saved their best for last as Nial Kidd burst through the line and carried a tackler with him as he dived over the line.
Windsor are without a match this weekend while Slough host Wallingford in their rearranged encounter on Saturday (2.15pm ko).