Bought a new computer, can't run shit (graphics card/specs advice)

Hey guys. Sorry if this is in the wrong place, but I noticed a lot of help threads are in Hardware so I figured my target audience might be here.

I bought a new computer the day before yesterday from Circuit City, an HP Pavillion Verde (a6645f), which is some model only sold through Circuit City. It was on sale and I was able to haggle it down a bit with my boss, so I got it, a two-year protection plan, a VGA cable and some audio minijacks for 620 bucks. How is this part relevant? I dunno, I just wanted to tell someone.

But anyway, I noticed I'm having difficulty running most anything that so much as resembles three-dimensions. I'm trying to pinpoint what the flipping hell the problem is, so I was looking for some advice/input from you guys. The specs on the thing can be found here:

HP Pavillion Verde a6645f Hardware Specifications

And here's the part that's probably most relevant, if you don't want to click the link:

Spoiler:

Hardware

Base processor
Athlon X2 (B) 4850e 2.5 GHz (45W)

*
2000 MT/s (mega transfers/second)
*
Socket AM2

Chipset
GeForce 6150SE nForce 430

Motherboard

*
Manufacturer: Asus
*
Motherboard Name: M2N68-LA
*
HP/Compaq motherboard name: Narra3-GL8E

Power
Power supply - 300W

Memory
Memory Installed - 5 GB
Maximum allowed - 8 GB (4 x 2 GB) (64-bit OS)

4 GB* (4 x 1 GB) (32-bit OS)

Other
Speed supported - PC2-6400 MB/sec
Type - 240 pin, DDR2 SDRAM

Video Graphics
Integrated on motherboard (see motherboard and chipset)

Expansion Slots
PCI - One
PCI Express x16 - One
PCI Express x1 - Two

Now, my knowledge of computers is limited at best, but I do know this computer isn't a fancy-ass gaming rig and isn't meant to be. But I'm also pretty sure that it should be able to do some light gaming without having to change my settings to the bare minimum and still get choppiness and slowdown.

My guess is that the built-in chip sucks ass and that I should get a video card, but I'd like to know what the resident experts think (and if they agree, what card they think would be best).

Thanks for your time, guys!

How ya doing, buddy?

Yes. Get a dedicated graphics card.

Thread over.

There's nowhere I can't reach.

I assumed it was the fact that it uses a built-in chip, but I left things open to discussion because I don't pretend to know anything about computer hardware.

Any actual suggestions for a card?

This thing is sticky, and I don't like it. I don't appreciate it.

Well, anything PCIE16 usually runs reasonably cheap. You could probably pick up a 256mb ATI or nVidia card at your local best buy for around $100.

I am a dolphin, do you want me on your body?

don't get anything too ZOMG EXPENSIVE though, or you'll need to throw in a new power supply too. Those high-end cards suck up a lot of juice.

I was speaking idiomatically.

ATI HD 4850 is a popular choice.

edit: Also, 1x PCI slot means mATX mobo. Might be wise to make sure that the case will be able to accompany a full size (height-wise) gfx card. If not, you may have to go with a low-bracket one.

What kind of toxic man-thing is happening now?