I +1 to Steve's advice about "contact your bank/merchant account provider".
With regards to where to install X-Payments - a separate server or separate VPS hosting account is recommended but if your bank/merchant account/QSA approves using the same hosting space with your main cart - well, you have someone to point at after all. Technically X-Payments can be installed anywhere and you don't have to hire our techs to do that, btw.
But with new X-Payments license ($1189) we include installation and configuration plus a free 1yr Instant SSL certificate so you get it live and running within days after purchase. I forgot at mention "1 month free support after installation".
http://www.qtmsoft.com/xpayments.html