Commercial ISPs offer typically about 5 MB in their standard subscription packages. If however you are writing books or are doing design work the requirements balloon quickly. For some their livelihood relies on what is here. Files Equally tricky. The minimum setup for a single user tends to be a dozen files, 0.5 - 5 KB in size.
Project related files can be huge though.
You might consider RAID for either speed or reliability. If you want extremely high speed and reliability you might be looking at other operating system and hardware platforms anyway. Web browsers often use a local cache to speed up browsing and this cache can take up a substantial amount of space and cause much disk activity. There are many ways of avoiding this kind of performance hits, for more information see the sections on Home Directories and WWW . The Linux Quota subsystem is capable of limiting the number of blocks and the number of inode a single user ID can allocate on a per-filesystem basis.