I have an earlier model (a135 with 2g ram 100g hard drive) and I dont know those two games, but I've played Halo and online games like Wolfenstein and Alien Arena with no problem.
Although, when i loaded DOOM, it would lock up towards the end of the game (towards the higher levels).
Hope this helps.
They do seem to be good machines though.
but there is a problem (occasionally; happened twice inn the tail end of two years) with start-up that may require you to remove, then re-insert the battery pack.
It's rare though.
Although there does also seem to have been some history of a connection problem with the power cord, on the earlier ones (same problem).