The Athlon II X2 250 Regor 3.0GHz processor is the perfect pick for your HTPC costing roughly $58.99, you cannot go wrong with this Dual-Core 2 x 1MB L@ Cache Socket AM3 65W processor. This processor should be all the power you need to run your HTPC to its full extent.
The Asus M4A88T-M HDMI Micro ATX AMD Motherboard includes 2×240 pin memory slots allowing up to a maximum of 8GB of Dual Channel DDR3 memory. A built in Audio chipset allowing 8 channels of sound using Realtek ALC887, and 6 x USB 2.0 real panel ports (5 onboard USB 2.0 ports), 1 x PCI Express 2.0 x16 port just in case you want to add a future graphics card for gaming etc, 1 x PCI express x1 port, and one PCI port.
All parts have a set of constituent products under “Budget Yielding Alternatives” that you may feel like considering if you want to go with something a little different (especially with computer cases), or better (as in a hard drive with more space, power supply with more wattage for future use, or higher quality RAM).