Currently, the best CPU/Motherboard combo under $110 available at Microcenter is the unlocked AMD FX 6300 hexa core CPU clocked at 3.5 GHz coupled with a Gigabyte GA-78LMT-USB3 AM3+ mATX motherboard. This combination provides a good AMD CPU that permits multitasking and gaming with its 6MB L2 and 8MB L3 cache.
Additionally, because the CPU is unlocked, overclocking is a breeze. The motherboard itself offers 4 RAM slots for a maximum of 32 GB DDR3 RAM running at 1333 Ghz, 1 PCI-E x16 slot, plenty of USB 2.0 and 3.0 ports, and 6 SATA 2 ports each clocked 3gb/s. Essentially, the motherboard is somewhat future proof(RAM and SATA are not), while the CPU is powerful and adequate for moderately high levels multitasking and gaming.