It’s almost a given that there is a potentially vast harvest of junk files, temp files and frap that can just go away.
Then the easiest thing to do is to get a big USB drive and move the file storage over there. Better yet, get two and use the second as a backup of the first.
If you can get the internal drive down under 50% full and do a defrag... performance will noticeably improve.
I try to clean up as much of that as I safely can. Is there a way to weed through all that frap and know what's safe to go and what isn't?
It's a Dell Dimension 2350. They don't sell those anymore. Can I increase the internal hard drive on that, or is the extrernal still my best bet?
A big USB drive would work best...though depending on how old the system is, you may want to also pick up a USB 2.0 card. They’re cheap.
If your system only has USB 1.0 right now, a large external hard drive is almost useless, because transferring large amounts of data is impossibly slow.