kyle, xampp 1.7.6 or higher no longer support mssql. however, you can manually include mssql as library in your xampp 1.8.5. you have to tweak the xampp after installation. but you have to backup all your xampp folder before doing so.
edit:
you can make the mssql 2012 R2 or higher. since you are using xampp 1.8.5 these are steps:
(by the way, this site is for newbie but since xampp is a part of development , i am including it.)
first you have to install xampp 1.8.5, your O.S. I presume is windows 2012 server or Windows 8...
Step 1. download MSSQL SERVER 2012 from microsoft website. (its free).
Step 2. find php.dll in your xampp/php/ext folder (If not there, move it there).
Step 3. then find the files php_sqlsrv_55_nts_vc9.dll and php_pdo_sqlsrv_55_nts_vc9.dll (if not there, download it).
Step 4. then edit your php.ini file and add the following lines:
extension = php_sqlsrv_55_nts_vc9.dll;
extension = php_pdo_sqlsrv_55_nts_vc9.dll
Step 5. restart your xampp (apache service).
Step 6. create the info.php file in your xampp/htdocs
Step 7. edit info.php with your favorite html/php editor and place the following:
Step 8. open your favorite browser and type this in your address bar:
You must be registered to see links
Step 9. it should display the entire page with information regarding your web service and supported database libraries.
Credits to Ragezone.