i cannot play

any of the original maps in counter-strike: source.
day-of-defeat: source.
half-life2: deathmatch.


Manufacturer:     
Dell Inc.
Processor:    
Intel(R) Pentium(R) 4 CPU 2.80GHz (2 CPUs)
Memory:    
502MB RAM
Hard Drive:    
154 GB
Video Card:    
Intel(R) 82915G/GV/910GL Express Chipset Family
Monitor:    
Plug and Play Monitor
Sound Card:    
SigmaTel Audio
Speakers/Headphones:    
Keyboard:    
USB Root Hub
Mouse:    
USB Root Hub
Mouse Surface:    
Operating System:    
Windows XP Professional (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_qfe.070227-2300)


help?

Video Card:   
>Intel(R) 82915G/GV/910GL Express Chipset Family

There's your problem.