I'm am looking to convert an old Dell Dimension V400 (cira late 90s) into a file/backup server. For an OS I'm going to be using lubuntu 10.04 (I like my debian packages), but disabling lxdm (its login manager) when I'm done so its always in CLI. The OS will be on its own disk, and on disk #2-3 (yet to be purchased) will be the network share. For backups I'm going to use bacula and 2 external USB 500 GB drives. Bacula will also be backing up 2-3 Windows machines. Files consist of mainly documents, program databases (IE QuickBooks), and other small files.
However I'm worried if this computer is just a little too old to do all this. I've already upgraded the RAM to 512 MB, and am probably going to invest in a PCI USB2 card and 100baseT Network card, but with a 400 MHz Pentium 2, it seems like any operation is going to take forever, backups especially, and the fact that I'm using PATA isn't going to help.
Is this computer simply too old and won't handle these functions, or can it pull it off? Is there another product that does the same thing and is not expensive? Should I consider RAID, multi-disk partitions, or other forms of internal redundancy? Is a SCSI or SATA controller + drives worth the cost?