upgrade 386 to 686

[pol]

forgive the possibility of overwhelming ignorance here...

i am new to PC architectures and have just realized that the compaq
box i have is in fact an old 686 box and not a 386. i installed the
386 version of ubuntu on it and now i am wondering if the only way to
upgrade to the 686 version is by downloading the entire ubuntu image,
again.

is there a simpler way, perhaps via synaptic or terminal, to upgrade
my ubuntu distro to the 686 version?

thanks for all the previous help everyone. my first incursion into
linux territory has been pretty exciting so far!

mulata