I need to upgrade. What should I get?

My friends tell me that Hammer crashes because my computer isn’t good enough to run it, so I guess its time to upgrade. What should I buy? Specifically, what are the minimum specs I need to have Hammer run without crashing every 5 seconds? It would be nice if I could keep as much as possible from my current system.

What I run now:
Intel Core 2 Duo, 2.13 ghz
3.5 GB of RAM (actually 4 but since I have a 32 bit operating system it doesn’t work right)
Radeon 5450 Graphics card
some hp motherboard that only has one gcard, and only supports 4 gigs of ram
Windows XP Media Center 2002 edition, SP3

(I put this in the gmod help section because I only need to upgrade so I can make maps for gmod, so don’t be all pissy about it)

Your probably fine, hammer just likes to crash a lot, seriously.
I used hammer baaaack in the day, we’re talking pre 1gig of ram days without any more issues than I have still today.

Make sure you optimize your maps, look up map optimization tutorials, if you have a lot of angles, or if things aren’t lined up on grids, it will overload your computer (and map) quickly!