Couple of questions

Hello,

first of all it think zen-cart is the best e-commerce application available, it's easy to use, easy to modify. But still i have some problems which i couldn't fine the answer s to.

1. I have a SSL installed and it works fine, especially in FF (it's rules) but in IE7 there is a problem with certificate, not so much as a problem but as a turn off for customers when they see this text:
   IE7 text:

There is a problem with this website's security certificate.

The security certificate presented by this website was not issued by a trusted certificate authority.

Security certificate problems may indicate an attempt to fool you or intercept any data you send to the server.
We recommend that you close this webpage and do not continue to this website.
Click here to close this webpage.
Continue to this website (not recommended).
More information

If you arrived at this page by clicking a link, check the website address in the address bar to be sure that it is the address you were expecting.
When going to a website with an address such as https://example.com, try adding the 'www' to the address, https://www.example.com.
If you choose to ignore this error and continue, do not enter private information into the website.

For more information, see "Certificate Errors" in Internet Explorer Help.

2. Since i use linkpoint API the customer get's 2 email, one from zencart (my site) and the other one from linkpoint, but in the mail from linkpoint there are zeros in the tax and shipping fields but the total payment equals to the zencart email with tax and shipping, is there a way to make it show.
   Linkpoint message:

Company: XXX XXXXX
Reference Number: XXXXXX-XXXXXXX-XXX-XXXXX

Subtotal: $20.82
Tax: $0.00 there should be $0.97
Shipping: $0.00 there should be $4.95
Total: $20.82

Thank you for shopping with us.

Thanks for your help!

Unfortunately your first question can only be addressed by you by spending money. All the browsers available ship with a certain number of root certificates pre-installed in the browsers root certificate store.
In the early days of browsers this status allegedly depended on how much fine gold changed hands, but today the likes of Microsoft and Apple seem to require a Webtrust or similar audit of the certificate issuing authority. This costs at least US$75 000 or so for the audit and upwards of US$10 000 per year for checking.
None of this has any particular relevance to the security of the person using the browser, and the message you quote above from IE7 is factually incorrect. All that it means is that that particular copy of the browser does not have a copy of the root certificate for the issuer of the certificate, and can be rectified by the browser user going to the issuers site and obtainging a copy of their certificate, usually by clicking on a button. After that, no more error messages or warnings.
You therefore, can either plaster your site with invitations to your customers to do just that, therebye enhancing their shopping and browsing experience, or you can shell out money for a certificate from someone who has a preinstalled root certificate in IE7. Oh, and it's a good idea to crosscheck the Firefox and Safari lists, cos they're not the same.
Self signed certificates aren't in the ballgame.