Age != bad performance, not in the case of C2Q's. They are still very viable today, especially with good overclocks. He would have to throw in a GTX 670 or 7950/7970 to start feeling the bottleneck of his CPU's architecture, as far as games go. When it comes to most other tasks, sure, SB or IB CPUs would beat a C2Q out in a fight.
Edit: if the computer is being used for some web browsing and a few FB games then there's absolutely no reason to upgrade, but if it's being used for video editing now instead of gaming more often than not then sure, upgrade away. Heck, throwing just a SSD into the mix for your OS and primary apps would give it a better feel.
as some have stated the Q6600 is still a decent processor and along with the reliable HD4850 you should still be running the latest games at reasonable detail and resolution ... i was also a proud owner of the XFX HD4850 which served me well... and i would of still be using it today but it developed a green line corruption fault which couldnt be fixed
motherboard bundles however are the way to go.. they are ideal for bringing your pc up to date without having to buy another complete system .... and a ivybridge bundle is probally your best choice,however you obviously need something thats going to be significantly faster than your current configuration and a core i5/i7 based bundle would be your best bet
ive looked around and the "Gladiator i5-3570K 4.60GHz Ivy Bridge Overclocked Bundle "( http://www.aria.co.uk/Systems/Bundles/Overclocked+Bundl... ) is a excellent bundle with some amazing specifications.. these include :
3rd Generation Intel® Core™ (Ivy Bridge) i5-3570K 6MB Cache Quad-Core Processor
• be quiet! Dark Rock PRO 2 Dual Fan Quiet CPU Cooler
• 8GB Corsair Vengeance LP (2x4096) DDR3 1600MHz Dual-Channel Memory (32GB Max)
• GIGABYTE GA-Z77X-UP4-TH Intel Z77 Socket 1155 DDR3 PCI-Express Motherboard w/ SATA 6G, USB 3.0 & 2x Thunderbolt - SLI & CrossFire Ready
• Graphics: Intel HD 4000 Graphics - IGP Supports DirectX 11
priced at £496 this represents good value and includes a decent 3rd party cpu cooler in the shape of the dark rock pro 2 ,one of the best overclocking air coolers around ... and its good to see corsair vengeance memory which is super reliable
a core i7 bundle would cost another £100 however the above bundle would be a decent improvement over your current system and not too expensive
you could however go the AMD way and go with a trinity based cpu ... the "Gladiator A10-5800K 4.40GHz Trinity Overclocked Bundle "( http://www.aria.co.uk/Systems/Bundles/Overclocked+Bundl... ) is £315 and you get a quad core A10-5800K which runs at 4.4ghz (overclocked ) .. and this is cooled again by the reliable dark rock pro 2 from be quiet ..... theres also 8gb of corsair vengeance ram running at 1866mhz and all this is based on the GIGABYTE GA-F2A85X-UP4 AMD A85X Socket FM2 with quad crossfire support ( http://www.gigabyte.com/products/product-page.aspx?pid=... )
both these are impressive bundles and would improve on your allready decent system specs....
however dont sell your current bundle for £60.. you should get £80 for the Q6600 alone so if you do sell look in the region of £130 which isnt asking too much
on the budget side of bundles the problem may be finding something that will be better than your q6600 however the "Gladiator AMD FX-6100 Six-Core Next Day Bundle "( http://www.aria.co.uk/Systems/Bundles/Next+Day+Bundles/... ) and has 8gb of ddr3 ram and a decent motherboard.. the FX-6100 is a hex core cpu with some decent performance ... maybe slightly quicker than the Q6600 but not by alot
then theres the "Xenon Intel Core i3 2120 3.30GHz DDR3 Bundle"( http://www.overclockers.co.uk/showproduct.php?prodid=BU... ) which is actually quite good... the core i3 however is only dual core ( 4 threads ) so this may be seen as a step backwards... in terms of performance the core i3 again beats the q6600 but not by much
hope this helps !