Re: Can a computer run without RAM? Does a full HDD make a computer slower?
No, a computer cannot run without RAM. I'd be interested in hearing about a computer that has the RAM hard-soldred to the motherboard. I've never seen a M/B that didn't have slots for RAM. The machine will refuse to boot without RAM. The BIOS will give error beeps (whatever code it is that indicates "no RAM") and that's all it will do. Take your RAM out and try it.
Yes, at some point how "full" the hard drive is will slow the machine down. You need a certain amount of freespace, or "slack" in order to give the machine room to work. I'd say anything over 80% full is bad.
Fragmented data is a more likely & significant cause of computer slowdowns, however. A very fragmented drive only 20% full will run slower than a defragmented drive that is 80% full.
I'd bet your school machines are slow because of all the protection softwares that have been over-installed on top of the OEM bloatware that no one has taken the time to remove. Is Norton or McAfee the AV software, in addition to 2 or 3 more? Are they restricting access to Myspace, Facebook, p2p filesharing, other objectionable sites & activities, etc...?
Software is a "load" on the system. The more software that is running, the slower it will run. The less software, the faster it will run. Hardware can be a bottle neck for certain and very specific tasks (Adobe Photoshop, Video Editting, graphic intensive games, etc...) but for basic browsing and email, a basic system like you describe should be good enough for most people. If these computers are slow, it's either because something is wrong, there is too much software running or both.