Dell optiplex 745 dt compatible graphics cards

My optiplex 745 desktop has a riser board

http://accessories.us.dell.com/sna/productdetail.aspx?c...

This should permit two full height cards although my riser board was then fitted with a low profile card. Do you have this riser boad in your computer?

My computer refused to boot and I thought the machine was dead until I removed the riser - it still works but I'm currently running off the onboad graphics which I find is okay for the web and flash movies.

I started looking for a replacement but was unsure how many watts I had spare considering the size of the power supply.

There are various site which have power supply calculators - after consulting some of these I came to the conclution I would need to go for the very bottom of the video card market - which didn't seem worth it.

This is the card that was originally fitted to my machine:

http://www.amazon.co.uk/Profile-X300-Graphic-Dell-Optip...

- so you may be able to purchase something like this. I decided it wasn't worth it as the onboard graphics do for me for now except i can no longer run two monitors.

Search for a power supply calculator - this is the first one I used :

http://www.extreme.outervision.com/psucalculatorlite.js...

If your hardware knowledge is as lacking as mine then its not very friendly.
It led me to believe I had around 30 watts to play with but its only a guesstimate due to capacitor aging (I think, maybe).

I do not have a riser board inserted but will buy one if it's restricting me in anyway, I have done research into the x1300 pro graphics card recommended and supported by dell as they offer the drivers on there website. I was thinking about something better knowing PSU restricts me quite a bit. I looked for a PSU replacement for the DT case and can not find one anywhere.

I have been looking at charts on power consumption and noticed the Radeon HD 4550 uses the same as a x1300pro with a requirement PSU of 300 Would this work?

http://www.tomshardware.com/reviews/geforce-radeon-powe...

A person also mentioned that this card works well on a 300 PSU

http://www.amazon.com/gp/offer-listing/B004I8W4VI/ref=d...