Best way to add wireless to an old windows Dell desktop

Tinie

My desktop is a dell inspiron 531. It has windows 7. Im wondering what is the best or cheapest way to add a wireless adapter to it? I have a USB wireless adapter that works decently, but it disconnects a lot from my router for a couple minutes, and speeds drop with it a fair bit.

So I was looking at these things: http://www.ebay.ie/itm/270564968219?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Would they work the same, with connecting to my wireless router?

Or is there something needed to add this to my desktop?

Here is pictures of the inside of my desktop if its of any help:

Monotype

I know it's not what you asked, but what about homeplugs?

http://www.amazon.co.uk/TP-Link-TL-PA211KIT-200Mbps-Powerline-Ethernet/dp/B004INVKP4/

Eboggles

Homeplugs! Seriously, look them up.

EDIT: Mono got there before me...

Tinie

Hmmm never considered home plugs. Cheers! Any cheaper brand alternatives that you know about, as I know £30 isnt going to break the bank, but im on a budget as its an old desktop, and would rather save as much as possible!

Serephucus

If you've already tried a cheap USB stick, your best bet is probably the homeplugs. PCI cards and the like won't really behave any differently. It's luck of the draw a lot of the time when it comes to USB networking yokes, I've found.

Monotype

That's as cheap as you'll get them when you factor in the delivery. There's 500Mbps ones which have come down in price (£36.63) which would last a long time for increasing broadband speeds.
http://www.amazon.co.uk/TP-Link-PA411KIT-AV500-Powerline-Adapter/dp/B0084Y9N3O/