New non-gaming pc.. Help please s;?

Hello guys.
My old pc isnt working anymore so my dad took a pc from hes work.
Back in time i was playing "World Of warcraft, Counter-Strike:Source, Modern warfare2" Without any lagg..
Now, im lagging even on the lowest video screen & effects.
Im not sure how i can find information about my pc, but i think this is some of the information needed.

Windows: Windows 7, 32 Bit.
Upgraded from Windows XP.
Some Screen Informations :
Chip-Type: GeForce 6100
DAC-Type: Integrated RAMDAC
Bios-Information: Version 5.51.22.24.2
Other information i found :
Processor: AMD Sempron(tm) Processor 3000+ 1.80 Ghz
Installed Memory(RAM) : 2,GB

I have World of warcraft installed on a external Hardrive, from my old pc which also was 32 bit. Works great on anyother pc's but not on this one.(LAggy)
Is my Computer not designed for games ? Or is there a way to make it work with games(:
I have tryed alot of Tutorials to make it work better ingame, but none of them helped me.. Only alittle bit..
Sorry for bad english hope you understand anyways, if any more information needed please tell me(:
~Sp1t0nTh3Gr0und'!

whs said:

The GeForce 6100 was often used with the Sempron processors. They come in two Southbridge flavors: nForce 410 and 430. They are both designed for very basic graphics tasks - not serious gaming. This combined with the Sempron 3000+ CPU is really not designed for games.

Well, i think i'll go ask my dad for a new pc this month then..
Thanks for the fast answer(:
++EDIT++
Would a new gaming Graphic-Card help ?
If so, how much would a good gaming G-Card cost?

Lol, i'll just go get a new pc this month xD!