Web surfing, watching online HD video, Excel, Word, watching DVDs, etc. Very little gaming.
For that use, an i5 is going to be overkill.
A home built system is always going to have better quality components, but is going to give the best value for gaming and 3D/2D rendering/editing.
For your use, a prebuilt will be fine. I didn't ask your budget range, but anything with a core i3 or the AMD FX-4100 or quicker will support you for a few years for your use.
I'm a big fan of lenovo