to pre-installed software

PDF files, you know, those documents that will look and print the same no-matter what computer in the world has a copy. Most windows computers come with Adobe Reader, pre installed, to handle these files. The down side is it's a resource hog. Before choosing an alternative I ran a few of them on my machine and compared their performance. After a few months, there was a clear winner. The requirements were it be compatible with the widest variety of pd files. It had to be light weight, Both in install file size and in it's consumption of system resources. Sumatra PDF is the clear winner.

Let's compare Sumatra PDF to Adobe.
Installer file: Sumatra, 4.4Mb; Adobe Reader. 40.5Mb
40.5Mb to download every time there's an updated version vs 4.4Mb
Sumatra wins
HDD disk space required for installation. Sumatra, 8.4Mb; Adobe, 335Mb
Again, Sumatra PDF wins.
Time required to open my sample of pdf files. For this I timed Adobe Reader opening 6 various sized files to set a baseline for comparison. I'll sumarize the results by just saying Sumatra opened all the files in 10 to 25 percent of the time required by Adobe Reader. One file took Adobe more than a minute to display on my screen. Sumatra opened it in 12 seconds.
RAM used by the application while having a pdf file open. Sumatra used, at best, only 7% of what Adobe used. To a worst case of 27%.
Sumatra PDF, There's a winner. Faster, light weight in HDD usage and RAM. I like the fact it uses less RAM. That means there's more available for ME.
You can download Sumatra PDF

Need to create a pdf ?
You don't have to drop $$$ t Adobe.
Get PDF creator. Installs as a Printer so even Notepad can make a pdf.

MEDIA PLAYER (audio/video)
from  FREE
I like to call it the Media player on steroids

It will play every movie and audio format file on the internet.
Comparing VLC to the "Media Player" Micro$oft windows has, VLC beats it, hand down.
if it's video or audio, VLC is going to play it.

Camera's and PICTURES
It is not necessary to install the software that comes with any new digital camera.
These are only "front ends" to windows utilities that transfer the images to your computer, with preset options. If you plug in the camera, without this software, you get to set the file destination,  With the included software, there's usually a wimpy image viewer and an option to share on their site, and order prints from them.  How often are you going to do that?

Just take your pictures, plug into the computer with the usb, or just the card and windows picture transfer wizard will let you copy the pics to your computer, where you set the options. Then use IRFANVIEW to look at them.

I could type page after page about how this beats Windows Picture and Fax vieweer.
It's a picture viewer, color corrector, crop, rotate, red eye reduction, and the list goes on --
Create slide shows on CD's or just a computer file. With music if desired.
Create html galleries for your personal homepage, or burn to a disk.
Manage your computers desktop background picture with it. (This will save room on your hard drive over using Internet Explorers -right click (on a picture) set as desktop background.)
Irfanview has so much functionality, yet is simple to use. I think you'll like it.
During installation, make Irfanview the default viewer for all common graphics files.
It's a checkbox you need to select.

INTERNET (I'll repeat these because I really think you should try them)
The only other good use for it is to download
Google Chrome(see chrome note). or Firefox .
Both are faster and  more secure internet browsers. I personally haven't used I.E. in years, other than testing pages.. I've seen more headaches (pages that don't work correctly) with I.E. on others computers, that display correctly with FF or Chrome.  FREE

This makes Internet Explorer #1, for downloading other browsers.
A nice accomplishment.