The personal part of a MySite is a site collection in a web application. When accessing you personal part for the first time, a site collection is created in the web application which you configured during the configuration of the Shared Services Provider (SSP).
During this SSP configuration, the config wizard also creates a MySite Host. This is a site which redirects you to your very own MySite when you try to access it. It also provides the public part of the MySite and other generic MySite pages.
Why am I talking about this MySite Host?? Because that MySite Host determines in which language parts of you MySite are shown. When creating a MySite (with multiple language packs installed) you are asked in which language you want your MySite to be created. But this is only the private part (the site collection).
On an environment I installed recently, I had installed and configured MOSS2007. After I created a SSP (sharedservices.
During testing of the portal I ran into some issues with some parts of the MySite being in Dutch and some parts being in English. After some testing I found out about the MySite Host (root of the mysite.
So if you are using language packs for MOSS2007 and notice that some parts of the MySite are in English instead of the language of your language pack, just delete the MySite Host site and recreate it using the localized version of the MySite Host template (can be found under the Enterprise tab).