IMHO,the reason that PC sales slumped globally is pretty obvious,the 'global' downturn.
Knowing Microsoft,with their 'more money than sense' attitude,it would NOT have occurred to them,that a global 'downturn' = less disposable income globally,therefore prices ought to fall,in order to maintain sales at the cost of reduced profits.
That is plain common sense, maintain sales revenue,keep tightening up on cost overheads & hope for increasing market share in a shrinking global business pool until the global 'recovery'.
In the UK, utility companies fleece the consumer, 'regulators' are bought & paid for by the utility companies along with Ministers in government.
That's the logical explanation for government indifference to utility price increasesm, that depress consumer spending, prolonging 'austerity' & reducing consumer spending from less disposable income.
As for replacing my PC rig, I have always assembled my own,I still have,as well as intend to keep my current rig for years to come.
It's comprised of a an ASUS Z77 Sabertooth mobo,3770K cpu,16GB Corsair Vengenace LP RAM, x1 INTEL 530 -240GB SSD,x2 INTEL 530 120GB SSD's & Nvidia GTX670 GPU.
It's really quick,it boots W7 64bit in 5 sec's flat,plays any game at good frame rates with no lag.
In addition,my EIZO FlexScan HD2441W displays top notch graphics,it cost £950 & was worth every penny I spent on it nearly 10 years ago.
I have troubleshooted hundreds of computers for people over the years, I find that a lack of regular maintenance & 'tuning-up' is a major factor in 'slow' running computers,as are app's like AV,which 'hog' resources.
Again,WINDOWS itself eats up drive space,with updates taking more than the O.S itself.
Any really 'old' laptop\desktop will benefit from a properly set up Linux distro to give a new lease of life.