If you post your specs like mobo model or pc model we can let you know for sure if it will work.
If you have a single core 3800+ I would geuss you have a socket 939 mobo for which they don't make cpus anymore. If that's the case you would have to pick up a 939 x2 off ebay or something.
1. i7920 @ 4.0 @1.25v, 6gb 2000mhz Trident, Enermax Revolution 1050Watt, DFI X58-T3eH8, GTX295 Co-op FTW, 2 x 500gb HD
2. Q6600 (G0) @ 3.5, 4 gb Corsair Dominator ddr2 1066, pcp&c 750, DFI LP DK X48-T2RSB PLUS, 2 x 4890 @ 950 & 1050, 250gb Barracuda x2 (Raid 0) 500gb Barracuda (storage), X-FI ExtremeMusic, JVC HARX 700, ATH AD-500
3. e5200 @ 4.1, 2gb crucial Ballistix ddr2 800, Crapy Dynex 500, DFI LP JR P45-T2RS, MSI NX8800GT 512M OC, 80gb HD, 1Tb .12
4. Gateway fx p-7805u