I didn't re-install Outlook when I re-built my laptop a couple of weeks ago. Gmail has been my preferred email client for years now and (almost) all my email addresses point to one Gmail account. It works well with the iPhone and having Outlook is really superfluous, except... Contacts and Calendars.
When I started using the iPhone, I started using Apple's me.com service to synchronize contacts between my iPhone, iPod and Gmail, but was very disappointed, it's slow and unreliable. What is more, it doesn't work with Google calendars.
While there are some solutions for the Mac to sync with Google Calendars, it took me a while to find a solution which works under Windows. After a bit of Googling, I found www.nuevasync.com which emulates Microsoft Exchange and lets you wirelessly synch Google Contacts and Calendars with iPhone and iPods .
While the registration site is a bit slow and clunky, once you get it up and running, it works like a dream. Enter an appointment in my iPhone and it shows up on my PC within minutes, ditto the other way around. Brilliant. And it's cheap: free.
The procedure for setting it up is pretty straightforward, just make sure you start with the right contacts and appointments on Google when you set it up, because the iPhone software will wipe everything before downloading Google's contact and calendar information.
There is a good description about the install at The iLife