Id say do both invest in lighting and a DSLR. quite simply with studio lights you can set up a home studio and charge people to do shoots and get a DSLR because theyre sooo much cheaper in the long run than films.
I have to agree with Andrew on this one. It will save you lots in the long run and if you have never worked with lights it will allow you to make adjustments right away and have a very clean finish for your clients. They will love it and soon you will make up for what you invested :)
Shara,
I'll go for both...but if you think your camera still can do the job...then invest more on studio lighting...lighting can be crucial in some shots... :)
I think the studiolight is very good! I bought it just one week ago and I really enjoy with it but now it just a interesting thing, not for money. I thing it's going to take about 3-5 month until I can do it well. After that I'll want to try to find some clients and it will be free for them - to get photos. for me it will be as a promotion. so if you have a camera and you can use it with light and you want to learn about light - buy a light:-)