Video card suitable for my PSU

Hi,
I'm looking for a video card for my desktop, but quite frankly dont know where to start. I'm not exactly familiar with video cards.
I read that you need to have a suitable PSU for the video card.

I bought my desktop (unfortunately) from Dell (.com), so i'm not sure how good the PSU is.

After a bit of digging around in my computer I found the tag on the PSU.
Model: DPS-300AB-24 B Rev: 01
Output +12--18A
+5V--22A
-12--.8A
+3.3 V -- 17A
+5 Vaux --2A

+3.3 and +5V total power can't exceed 160W
Max output - 300 Watts

I really dont understand anything from that.

So basically i'm trying to understand what type of video card I would need (hopefully without upgrading my PSU) to be able to game on the desktop. (medium/low setting on games that are coming out)

Oh and from what I understand from GPUz, I need a PCI bus card. (but I've read that Dell Inspiron 530 uses PCI-E =/ )


Thanks

ok so basically you have a 300 watt psu, any budget you have? and card preferences like brand? and what you'd like to achieve with this upgrade?

lol sorry about the no specifics.

Mainly to be able to game (games like Mass Effect, Splinter Cell Conviction etc etc) on medium/low setting.

Budget around 50$ (that is if I dont have to replace the PSU)..
Thanks.

hm....... in that case try something like one of these
Newegg.com - SAPPHIRE 100274HDMI Radeon HD 4350 1GB 64-bit DDR2 PCI Express 2.0 x16 HDCP Ready CrossFireX Support Low Profile Ready Video Card - Desktop Graphics / Video Cards
or this is the one i'd recommend
Newegg.com - HIS H465FS512H Radeon HD 4650 512MB 128-bit DDR2 PCI Express 2.0 x16 HDCP Ready CrossFireX Support Video Card - Desktop Graphics / Video Cards
but unless you can spend more thats about the best i can suggest