The one on TigerDirect has many factors that render it, to my mind, unsuitable for gaming.
1) It's a PC Chips board. Upgradeability in this area will be extrememly limited.
2) That board is a Socket A board. These have been phased out in favour of the 64-bits which that board will not take.
3) The chipset is SiS, which, IMO, has never really performed all that well.
4) Onboard graphics which are crap for anything intensive.
5) 128Mb of Memory, coupled with onboard graphics which take a chunk (probably at least half) OUT of that 128 stick means this system will struggle to do anything.
6) Its a Sempron processor. These have never been designed for gaming.
Value wise, for what you want, I'd avoid it like the plague.
As for the one on CyberPowerSystem.com:
This system will fly. I would take the memory up to 1Gb though and the X800 is a nice card, and can always be swapped out later for a better one when they come out and prices come down.