moshu's right you need to contact your host.
looking at the whois data for the site that the links are pointing to it looks like you're dealing with something which might be able to be dealt with.
A R T E S O N O R O dot ORG is registered to a Jose Carlos garcia sanchez
His DNS servers are pointing to TECHNORAIL.COM
TECHNORAIL.COM was bought by
Santini, Susanna email@example.com
Piazza Garibaldi 8
Soci, AR 52010
+39.057551571 Fax: +39.0575515790
(used to live just down the street from Piazza Garibaldi)
Aruba.it is an italian web host.
So the second thing I would suggest doing after contating your webhost is to contat aurba.it and tell them that they've got either a comprimised account or a spammer on one of their servers.
You're also fairly lucky because the site in question has been up and running (on wp at least since July of 05) Normally these sorts of things are going to be pointing to MFA sites which pop in and out of existence all the time. So this looks like it's a real person. I was able to catch the source to one of the pages before it loaded the redirect and it looks like whoever created the a r t e site is the same person who inserted the redirect...
(I've saved the page in question if you want a copy I'll send it.)