PC or iMac ?

Hello all ,

I want to know which is better choice for me , iMac or PC ......

I currently use Dell XPS 430 , and i am using a low range lenovo laptop for college , softwares which i currently use are : AutoCAD , MATlab and Multisim (For designing circuits).Personally i don't use any other software apart from browsers and media players on my desktop , Just iTunes for consuming media and two games , one is called cnc3 tiberium wars (only online) , playing it since 2007 and chess , are only desktop games i play that too once or twice a month , as strategy games on iPad/iPod not very good.I used to be a hardcore gamer like 3-4 years back , not anymore.We recently thought of moving to a bigger home in 2-3 months , so an extra TV is needed , any TV which must be atleast 40 inch screen size or even bigger , currently i hooked a 42 inch LG 3D-TV (using like 2-in-one , consuming multimedia along with some 3D stuff and also as PC monitor maintaining like 1.5 meters eye distance while using it as monitor) .I use same Vista OS which came pre installed with XPS back then.Thought of upgrading to Windows 8 soon when it releases.Currently i am using laptop way more than desktop while my little bro (we have like 8 years gap of age) , just started using computer , he is around 12.

So this is what i thought :

Mountain Lion coming very soon and also iMacs will be refreshed , I currently use an iPad 3 and iPod Touch (Since Onkyo 7.1 music system only support iPod/iPhone Docks) , ML is bringing all iOS features and integrates them even better than Lion before , While Windows 8 really benefits only people in Windows eco system i.e Windows phone users , xbox and surface users , Right now we need an extra 40 inch TV as home is bigger one as i said before , So there are 2 options :

1.Sell Dell desktop (or give it away in our office for good use) and Give away LG TV/Monitor to hook it somewhere in new house and buy an iMac ?

Or

2.Keep all things as they are now , and buy a new 40-46 inch TV for house instead of replacing my PC.

UPDATE :

I took a pic of my current setup :

House is very old , like 30 years old , and lot of clutter at back with wires everywhere , setup may look wierd but its 2-in-1 approach for using display as TV and monitor :

Photo_medium