wow, that sucks. i apologize for saying that.
get a P4 2.4 or higher, you won't be dissapointed.
512 memory at least for modest systems
no cd burner or dvd-rom?
no AGP slot?
that PSU is kinda weak too
is 40 gigs enough for your harddrive, i had 40 once, then i went up to 80, and that wasn't enough, now i ended up with a 250, but that's just me, i use my comp to it's full potential.
western digital for harddrive at least 80 gig
intel P4 proc 2.4 ghz or higher
name brand memory, 512 stick
antec PSU, at least 300 watt
maybe a cd burner, plextor or lite on brands are good (burners are a dime a dozen for a speedy one)
find a mobo with an AGP 8x slot, if not a PCI-ex slot, it's a must have if you want to ever get a video card.
this is what i would reccomend for a low end pc.
what exactly is a modest budget and what do you plan to use the comp for? like websurfing, music, games, word doc apps, downloading, etc...