Hello, and welcome.
If all you're looking for is a simple media center, there are many others to try.
This is a smart home platform, the first of its kind, managing media, lighting, climate, telecom, and security for an entire house under one system.
I would suggest reading the FAQ in the wiki:http://wiki.linuxmce.org/index.php/FAQ
Now, to try and address your hardware:
* your Intel 915 will work in the Basic (UI1) and Masked (UI2 medium) modes. To use the full alpha blended interface, you will need at least an NVIDIA 6200 card.
* Your MCE transciever and remote will work. However, I recommend replacing it with a USB UIRT, a much better transciever with IR learning capability, very useful for controlling your A/V gear. http://www.usbuirt.com/
* Please use supported network hardware. Do not argue wtih me. Get two NIC cards, even if you only use one, connect the first NIC card to your internet modem, the second to your internal network's switch. Your LinuxMCE system will become the center of your network.
* For tuner cards, use a PVR-150/250/500/USB2 for SD, or an HDHomeRun for HD.
You should install LinuxMCE 0810 Alpha 2, according to these instructions:http://wiki.linuxmce.org/index.php/LinuxMCE-0810_alpha2
Follow these rules, and you'll have a painless, and seamless installation.