portableapps has lots of softwares that can be run easily on a thumb drive.
create a truecrypt(truecrypt.org) volume in the usb drive and keep the personal files.
you should run a very good anti spy ware if you are browsing sites and I found
superantispyware.com (is a very good anti virus and is free for basic use) is able to scan and catch unwanted things realtime.
PortableApps.com is the world’s most popular portable software solution allowing you to take your favorite software with you. A fully open source and free platform, it works from any synced cloud folder (DropBox, Google Drive, Box, etc), from your local PC on an internal or external drive, or on any portable storage device (USB flash drive, memory card, portable hard drive, etc) moved between PCs. With millions of users all over the world and a full collection of open source and freeware software, compatible commercial software, and partners in hardware industry, PortableApps.com is the most complete solution for life on the go.
PortableApps.com was founded by John T. Haller, the developer behind numerous portable applications including “Portable Firefox” which started the portable software trend. We’ve been making software portable since March 2004. Today, our team stands at over 100 developers, translators, application packagers, designers and release testers with millions of users and over 770 million apps downloaded. Our goal is to centralize the knowledge and development of portable software efforts and build a single, open platform which any software or hardware developer can use.