lightbox auto-popup on homepage

Will search engines read text in lightboxes

[doitright]

Hi

We have a well respected website, whose homepage has ranked well in Google for an important (to us) Search Phrase.

Recently, we have been investigating the impact on signups of a 'lightbox' / alert box which pops up automatically whenever a new person views our homepage. The lightbox just contains some information and a form encouraging people to signup.

Will this auto-lightbox affect our Search Engine position for our imporant phrases? Or does Google look past the lightbox.

Thanks for any help

[Hoople]

Those that populate the pop-up with text from an on-page hidden div (CSS display:none) will be seen by Goolge.

Other lightbox implementations use data blocks within the js to populate the pop-up. Google claims they can read js, but will the form's content have a lesser influence on that page's ranking than the hidden div?