In support of what LevelHeaded says, braces, dunno - the only time i've worked with an athlete to use any kind of device has been where there is such an injury and pain that temporary support is required to function.
Since it doesn't sound like that's the case, i'd strongly encourage giving a mobility program a go.
There's an expression and i wish i knew the source "we get the bodies we deserve"
likewise the SAID principle - specific adaptation to imposed demand: our body adapts to what we practice.
BUT on the plus side, we're adapting all the time. So you can re-adapt your body out of your desk jockey effects with practice in re-educating your joints on how to move out of that effect.
you also have woolf's and davis's law on adaptation working for you, too.
IT's less about "constant pulling" than movement practice and strategies to keep moving.
I have lots of folks telling me when they come in with sore shoulders etc "i know i have lousy posture" and heh, that's largely ok - don't care how you slump sometimes; it's how do you move? Do you move?
So, staying mobile - ensuring that for all that flexion, you get complementary extension - you can come back.
2 things i'd suggest specifically for your issue
1st and foremost: dynamic joint mobility program - there are a bunch - i personally like z-health
here's some info - up to you.
2nd - kettlebell swings and kettlebell turkish get ups are fabulous for the kind of muscle work level headed describes. Enter the Kettlebell (http://bit.ly/9BvSdq) is one v.good program to get going with that approach. IT's one several of us user with a lot of our teams: swings and get ups; swings and get ups.
hope that helps.