Both cameras have good points and niggles, so I place none ahead of each other tbh,
The canon offers less noise in it's images and can be used with a purpose designed battery grip to extend battery life and give a better feel when used in portrait situations, it's silver looks don't suit everyone but they keep the 300 series branding of it's film based counterparts. A black version can be bought now from jessops, or importing from HK.
I had a 300D before moving up to the 20D, and it produced some great images during the time I had it.
The NIKON takes advantage of being almost a year behind the canon and made use of this time to spec a camera which redressed the niggles found on the 300D.
Customers wanted an entry level Dslr that started up quickly, took as many shots as possible and be BLACK!
and to NIKON's credit they gave the public exactly what they wanted, the d70 is a very capable camera indeed.
As mentioned earlier, buying into the Dslr market your buying into a brand which once selected will be expensive to change as your choices of lens and flash are specific to the body.
If you have no kit to start with, you have the power
Let the shop sell you the best kit, but make them work for the sale. Test both bodies and get them to do a print out for you, this is where the specialist shop comes into it's own.
Good luck with your decision.