Install 8.04 on old compaq laptop

Bare Minimum requirements

It should be possible to get Ubuntu running on a system with the following minimum hardware specification, although it is unlikely that the system would run well. You should use the Alternate install CD to attempt such an installation.

    * 300 MHz x86 processor
    * 64 MB of system memory (RAM)
    * At least 4 GB of disk space (for full installation and swap space)
    * VGA graphics card capable of 640x480 resolution
    * CD-ROM drive or network card

So yes you can
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You can go for
Low-spec computers (Xubuntu)

If you have an old or low-spec computer, using a lightweight desktop system such as Xubuntu is recommended, as it should make more efficient use of your system's resources.

If your system has less than 192 MB of system memory, use the Alternate Installation CD.

Note: If you have a low-specification computer, certain features may be automatically turned off to conserve system resources. For example, if you have a graphics card with only a small amount of video memory (VRAM), the boot-up screen may not be shown.

Follow this link for detailed instructions: Installation/LowMemorySystems.

Minimum requirements

    * 166 MHz processor
    * 64 MB of system memory (RAM)
    * At least 1.5 GB of disk space
    * VGA graphics card