6.1 from what I know of it contains an upgrade to PIE which allows tabs. Also, there's threaded SMS (again my knowledge is 2nd hand).
I like Opera 9 browser but if you install be careful to take a version which allows uninstalling which is mostly what you'll now find and it will likely be indicated. Also, there's Opera Mini which many swear by.
Skyfire browser is now a personal favorite but others like Netfront.
Search for all of this and you'll find tons of comments on each of these subjects. Have you installed HTC Home Customizer to change the way things look? It's at
www.pocketemu.com.
If you've done a bit of customizing and adding program before you change things use a backup program in case things get messed up so you can go back. Otherwise, you can always do a hard reset to get back to a stock out of the box device.