I've heard that it can be more difficult to get extra hardware for Dell computers than 'clones' (this name is so outdated and makes no sense - Dell would seem more 'cloned' than the box that I 'cloned' here next to me). Is this true? jam13, what kind of third-party components do you get, and what are the restraints / considerations in buying? Can I just, e.g., buy an extra stick of Kingston memory, a new HD, a DVD writer, etc., and stick them in the Dell without probs?
The upgradable components on the dimension range are pretty standard - hard disks, memory, cpu, CD drive etc. - and you shouldn't have any real problems. I normally use Kingston and Crucial memory as they are model matched which saves trying to work out the memory timing/speed requirements.
The only real exceptions are the power supplies, which are sometimes non standard in form factor or wiring, and mainboards.
Servers can be more complicated (drive caddies etc.), but drives and memory should still not be a problem.
The other thing to bear in mind if you use third party components is how it affects your warranty.