Think outside the box!
I have a Windoze computer at work also, but don't use it for GTD at all! My iPad sits alongside the Windoze computer, with an Apple Wireless keyboard, and with a iPad charger with a longer cord.
I enter most all GTD inbox items straight into OF on the iPad. If there are specific work e-mails that should be incorporated, I just forward them to one of the e-mail accounts active on the iPad.
All OF items are synched through iCloud to my iPad, my iPhone and my Macbook Air. It is really not that hard to use GTD via OF at work, without using your Windoze PC. This is not really that different that when I used a Time Design planner for GTD, but the back-up and multi-device capability is far better.
Just another approach for your consideration.