Hey Karl, Before we cover RAM, make sure your new laptop is running a top notch graphics card and a high end i5/i7 processor. Couple this to 8GB+ of RAM and your machine will probably take over the planet and call itself Skynet;-) 8GB of RAM will happily cover all of your needs and you will notice a speed/performance increase when editing in Photoshop. (Ensure your using CS5 or CS6 for optimal use of resources) If you are a professional and time is important, then 16GB (and even more) of RAM is highly recommend. Basically, the more RAM (and of course faster processor/graphics card) you have, the quicker you can complete tasks.
You could of course go a step further and run your system off a SSD (Solid State Disk Drives) Running Photoshop CS5/6 off a SSD is amazing! The speed transfer and performance is incredible! 8GB fine, only likely to need more if you're into something that needs big files in memory like video editing - and even then the effect of not enough memory is probably just going to be slower performance as it uses swap-to-disk. I assume you're using 64 bit Windows, otherwise the operating system can't address more than 4GB. Do check what memory slots are availlable. If the 8GB fills all slots then a future 16GB upgrade will mean buying 16GB rather than a second 8GB module (as its a laptop there may only be a single memory slot anyway).
The Mac mini can accept up to 64GB of RAM, and technically, it is user upgradeable. Although the process of getting into the Mini, and doing it yourself isn't going to be easy.
As commented in another thread yesterday - are you sure laptop is the best choice? How things have changed since my ZX80 in 1980 with 1kb of memory! (That wasn't enough!). How much RAM are you using now in your computer that you use for Photoshop? If you are using more than 8GB, then you would notice a difference going down to 8GB, butnot so much that it isn't usable. Upgrading later on is simple and cheaper to do yourself, plus you have the option to find higher performance RAM with lower latency than what may be offered as an upgrade with your laptop purchase. If the laptop includes a 1+GB graphics card, then 8GB can be plenty enough to not need the extra 8GB with such a high price.
Some modern and light linux distros can run in RAM only, from a USB key or dvd disk. Advantages are: incredible rapidity, and.rapidity.
![8gb 8gb](http://i2.cc-inc.com/prod/40658000/40658038_xxlg_0.jpg)
But if some programs there are resource hungry, RAM could quickly become limiting. I may be wrong, but OS running in RAM could become trendy, especially in small gadgets such as cell phones, cameras, etc. I havent seen that yet, but I run a linux OS in RAM, and its incredibly fast, but when I run a hug program, it slows down; I will probably add more RAM to circumvent this problem.