Since I've been using Win7 on my desktop, I've been finding some nice ways to integrate it into my daily workflow. My primary machine is a 2006 Macbook Pro 15", and so far the two have been playing well together.
Here are the main programs/utilities that I'm using and some commentary on each.
This is such an integral component that it's listed first. All the files that I'm working on or have ever worked on are in here, and they're available on both machines and through the internet with almost no overhead.
Microsoft Office (both)
This is a requirement for work, and I've got it installed on both machines. The beauty of it is, with Dropbox, I can work on the same file from both machines.
Notational Velocity (Mac) / Resoph Notes (Win) / Simplenote (iPhone/iPad)
Synchronized notes available anywhere? Very yes. Simplenote is the glue that holds it all together, and I can access all my notes from my computers, my iPhone or my iPad. I could sync them all in Dropbox, but I love the Simplenote App (iTunes Link) on the iPhone/iPad and the interface is amazing. I was especially impressed with Resoph Notes on Windows. The interface is simple and it syncs perfectly.
Terminal & X11 (Mac) / SecureCRT (Win) / XManager 3 (Win)
My Mac has an advantage here because Terminal is included and X11 comes with the developer tools (free to sign up and download). On Windows, SecureCRT and XManager are great 3rd party tools, but they run about a few hundred dollars each. In either case, these are my bread-and-butter tools for SSH, Telnet, and xwindows exporting.
Cord (Mac) / Windows Remote Desktop (Win)
Windows would have a slight advantage since Remote Desktop is built in, but Cord is the best RDP client that I've ever come across. And it's free. In fact, I wish there was a Windows version of it.
Google Chrome (Win) / Safari (Mac)
Mac OS X comes with a pretty good browser, but Windows, on the other hand, doesn't. Internet Explorer is getting better, and I'm hoping IE 9 is decent, but out-of-the-box, it's crap. I used to go with Firefox, but Chrome is much faster and I can do without the plugins.