At the moment I have a standard ATX Case, an old one but since upgraded my computer and its causing alot of overheating therefore, I am looking to buying a new case that will offer good ventilation and USB 2.0 and Speaker/Microphone jacks on the front panel that DOESN'T come with a power supply.

Can anyone recommend a suitable option?

Theres loads on ebuyer, i bought one for my sister, only cost about £15 including delivery, has front usb and speakers/mic ;) -- really nice to build into, and studry, not bad to be honest... (for a 'cheap-o' case) http://www.ebuyer.com/UK/product/108273

My GFX card really does kick out some heat though - as do the 2 x HDD I have in.

Apart from dimensions, whats differance between Midi and Atx?

I would recommend Antec branded cases, I built a machine which I wanted to run both cool and quiet, Antec cases often use 120mm fans which run at lower speeds (so are quieter) but still move the same volume of air as smaller diameter fans.

I have four SATA drives, including two 10k RPM WD Raptor drives in my case and it runs both cool and quiet.

A very well built case made from quality materials at a reasonable price.

as ghozer says. the cheap casecom cases from ebuyer are really good for the money, ive got one here & i got one for my friend too.

they do a few different ones, most have plenty of room for fans & air circulation as well as drives, etc.

Antec p182 - it's soooo good, and definitely worth the money (£75 or so).

I'm running a Radeon x1650 with passive cooling and it barely tips 39c - mostly thanks to the fantastic ventilation this case offers.

Weighs a ton, though.

This is available from Ebuyer as quick find code 125969 - £19.99 inc VAT

http://www.colors-it.com.cn/03_products/pro_show.asp?pro_id_search=120&max_id_search=4&min_id_search=33

although max rear fan size is 92mm it looks a nice lightweight case - read the reviews for more info.

Ended up plumping for this one...

http://www.ebuyer.com/UK/product/103565