How much free space does Windows XP SP3 require after install?

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I have an installation of Windows XP SP3 on a “computer” that only has a 1.8 Gb HDD. I say “computer” because it is a piece of laboratory equipment that runs Windows, and is not an actual computer. Unfortunately, there is no way for me to increase the available storage for the device.

After Windows and the Service Pack were installed, the available space dropped to ~750 Mb. Because these devices are going to be connected to a Military network, Anti-Virus is required. After installing Anti-Virus and running any additional updates I will be left with <100 Mb on the C: drive.

Is it safe to allow Windows to run with such a small amount of space? I have been searching for a few days and haven’t been able to come up with a definitive answer.

Any help is appreciated.


“Is it safe to allow Windows to run with such a small amount of space?”


It won’t be long before the PC becomes unusable due to No free space on the drive.

You will need to start deleting anything you can that is not needed like temp files, also you can do a disk cleanup.

Sounds like it is time for a New piece of Lab equipment.

If this is a military network, and/or there are any Microsoft contracts in place, take a look on your Software Assurance / Licencing page for a download called “Windows Fundamentals for Legacy PCs”.

This is a cut down version of Windows designed for computers with much older hardware (Can be installed on a 486!)

However, if you want standard XP, take a look at disabling pretty much everything such as System Restore or even using nlite to remove features that you do not need.

Also, if you are required to use their AV, fair enough – if not, take a look at Microsoft Security Essentials, it has quite a low footprint.

All this being said, if I was you, buy a new hard drive, even second hand – or a £5 adapter and a old Compact Flash adapter – someone must have a 2/4GB card laying around – that would be an upgrade!

Use something like nLite to create a cut down version of the Windows XP installer and then use that to install onto your “computer”.

People have used this to cram Windows XP onto netbooks (back in the days when they had tiny solid state drives and ran Linux) although you’re naturally going to have to sacrifice some functionality.

Simple answer: It’s not safe.
If the system RAM memory gets short, windows will save in the HDD the information it would preferably put in the RAM because RAM is a lot faster. If windows runs out of memory RAM and HDD, windows can crash, the software running in windows can crash… and so on.

So unless you are sure that windows won’t run out of memory, it’s not safe to use in this system.
You can check the amount of memory windows will use in the HDD when the RAM runs out, going in: system properties-> Advanced tab -> Performance section -> settings -> advanced tab -> virtual memory section -> change.

Attached is a picture of the windows you have to go thru to get there.

This allocation of memory is inside a file called pagefile.sys in C:
If you have enough RAM and enough pagefile it’s safe to run windows on this system.

You can check if windows is allocation any space for hibernation and if It is and you don’t need it, you can deactivate it to save more space.

For a deeper understanding:

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