Too many questions so I'm going to stick to asking/summarizing what is important. On Lenovo's website I've priced out identical specs for the L540 and E540. Prices are identical so it seems that the differences are in the shell.. 4GB of memory is enough.. i3 4000M is the best deal.. Is it worth spending the extra $110 to upgrade from 1366x768 to 1080? Windows 7 or Windows 8??? As of now I'm using my father's laptop which is an Acer Travelmate 4750-6422 i3 2350M Intel HD 3000 4GB DDR3 500GB HDD It certainly feels like it's built rock solid and I've never felt it get hot. Though I don't like the keyboard much as it wonks out from time to time. Also the system does go through micro hangs/freezes.
The $110 upgrade for 1080p is up to personal preference. If you are going to be using the laptop for watching the occasional movie and such, you might prefer the 1080p. If it is strictly business use, 1080p won't bring much of a benefit other than added screen real estate (which is practically pointless on such a small screen).
Windows 8 is faster and of course going to be supported for longer. I genuinely prefer it over 7 too although many would disagree. 1080p, your choice, I wish I had, I can't fit enough code on screen without dropping font size, same may go for writing lengthy documents (although I did get on just fine for that, programming was my main concern).
Stay away from HP, they are complete trash. My bro had to send his PC for fixing more than 10. Always a motherboard problem, or won't turn on. A good business pc is the Lenovo ThinkPad. My dad has one and it runs very nicely.
I'm suddenly contemplating saying "fuck you!" to the whole laptop idea mainly because I'm going to do lots of typing and the whole laptop keyboard concept drives me bonkers! I'm going to look into building a desktop though it would have to be a mini tower so I'm going to look at that thread started by mrkelkel. Only question then would be which CPU socket I should look into. The last system I built was my gaming rig LGA 1155 with an i7 2600K so I imagine there's newer and/or better sockets to consider building upon? Off to Google I go...
1150 is the current non enthusiast socket intel wise. AM3+ and FM2+ are current AMD sockets depending on if you want a proper FX series chip (AM3+) or an APU (FM2+) with later athlon and phenom parts also fitting AM3+ and a few athlon parts still being made in FM2+ for some reason - can't recommend going there particularly, alright for a budget build but otherwise obsolete.
Going for an 1150 socket CPU would probably fit you best. Something like an i5-4670k would definitely suffice, if not be too much for a business oriented machine. An i3 might even be a viable option.
I know all mobile i3 parts do, I havent checked on desktop parts (which are mostly dual core but there are quad core models). Desktop i5 parts generally do not include hyperthreading (I think there are 2 which do but the i5s are all quads anyway (except mobile)). Desktop i7 parts all include hyperthreading. - - - Updated - - - There is a pentium chip in 1150 socket which is quite interesting. Its only a dual core model without hyperthreading, but its only £53 and has been shown to reach 4.8ghz overclocked on air cooling. With only 2 cores and no hyperthreading, there isnt alot of multitasking to be had there, but haswell at 4.8ghz, thats a heck of alot of single core performance and its coming cheap.
All i3 CPUs are hyperthreaded dual cores. All i5 are quad cores with no hyperthreading, and all i7 are hyperthreaded quad cores.
I'm probably going to settle with the Core i3 4360. Now I'm looking at Micro-ATX motherboards. -edit I have two spare sticks of 4GB RAM: Kingston 8GB Kit KTA-MB1333K2/8G so if I can find a mobo that supports this memory it saves me from an additional cost.
I didn't know about hyperthreaded i5's, there are some non-hyperthreaded i3's though. You're right about the 6-core i7's, there's also an 8-core model (5960X).
I just returned from the local CanadaComputers retail store just so that I could get a visual on things. I didn't realise that the micro-ATX cases were so freaking big which means I'm going to go for a mini-ITX build.
LGA1150, i3-4130 cm elite 120 - http://www.amazon.com/Cooler-Master...8&qid=1410979536&sr=8-1&keywords=cm+elite+120 and a nice mechanical keyboard. you will be happy.
Asus H81I-Plus - $80 Intel i3 4130 - $150 If you have 8GB of RAM that should be just fine, you'll just need a case and PSU.