I bought my IBM 3.1 gig w 3gig ram (room for 4),500 gig SATA on ebay for $65 that included free shipping and restore disks . Not lighting fast but workable ! I saw a 4 x 3.6 processor w 12 gig ram installed sever mobo on ebay for $99 a few days ago . You might just need a power supply and extra fan to cram that in your old tower . I bet your son could make that happen very cheap .