international domain DNS redirect and se visibility

[valeria_vi]

i am not sure i'm asking this in the right forum, so mods please move if nessesary.

we have a web site blah.com with a splash page that redirects to blah.com/us if people choose US as the country, blah.com/ca - if they choose Canada.
Our sister company in Canada holds a domain blah.ca and they used to have a splash page at that domain with some text on it and when people clicked to enter the site, they were taken to blah.com/ca
now they decided to eliminate the splash page of blah.ca and do a DNS redirect - whenever somebody types in blah.ca they are automatically taken to blah.com/ca
i know absolutely nothing about how regional search engines work, so could you please explain to me how is that gonna affect their search engine visibility (especially, but not only in canadian search engines)?

[Shak]

wouldnt sub domains be better in this case?

ca or canada.blah.com and usa.blah.com? you could potentially get multiple listings in places such as Dmoz along with having google recognise the subdomains as seperate entities.

I will let someone else answer the redirect issue, as my knowledge in that field is limited.

Shak