There are a lot of threads on related subjects in this forum. Basically what you buy depends on what you expect from the PC and how much HDD space you are likely to need (ie the amount you expect to load onto it). You should also remember that once in use it may be found `ideal for other jobs`.
From what you have said a fairly basic PC should suit your needs. I would suggest you look at this post click here and the links I gave. You could also do worse than search these forums for other recent threads which may help.