If you know someone with an account with Frontosa, grab the Corsair or Kingston DDR-400 (PC3200) 200-pin SO-Dimm memory (backward compatible with the DDR-333) :
Corsair 512MB - R266+VAT
Corsair 1GB - R727+VAT
Kingston 512MB - R292+VAT
Kingston 1GB - R779+VAT
Works well with the Dell's - upgraded my Latitude D510 and Precision M70 with 2x 1GB's each of DDR2-533 a month or so back and made a big difference...
If you don't know someone with a "dealer" account you can also buy from Cyberdyne Systems in Johannesburg.
Super*Talent® 512Mb DDR400 200-pin 400Mhz NOTEBOOK SO-DIMM R 262.20 (incl.)
Super*Talent® 1Gb DDR400 200-pin 400Mhz NOTEBOOK SO-DIMM R 552.90 (incl.)
Kingston 512Mb DDR400 200-pin 400Mhz NOTEBOOK SO-DIMM R 353.40 (incl.)
Kingston 1Gb DDR400 200-pin 400Mhz NOTEBOOK SO-DIMM R 872.10 (incl.)
Both Super Talent and Kingston come with Lifetime warranty, not sure about Corsair.
I personally go for Super Talent because the price is very good and the make some very fast modules (especially their DDRII-800 modules, I haven't seen anyone beat their price per performance yet, at least in SA).