To get valuable system information, like 'system installation date and time'

If you want to get operating system and hardware related information about your computer, then you need not download any tool for the same. This information includes details like operating system (OS) version, OS installation date, processor (CPU) type/class among others.

You get retrieve vital system information by following these steps:
1. Run command prompt. 
[Hint: you can run command prompt  by either of the ways: 
 a. Start --> Run... --> type
cmd
and hit Enter key.
 b. Start --> Programs --> Accessories --> Command Prompt] 
2. In command prompt, type systeminfo.

The computer will produce a lot of useful info, including the uptime.

To Save System Information to a File:
If you want to save this information to a file, type  
systeminfo > info.txt
in command prompt. This creates a file called info.txt you can view later with Notepad or any other text viewer.