Need Advice On Gear Upgrade

I need to give my recordings a boost and want to upgrade my equipment but can't really decide where to start. I know a lot of you have first hand experience with most this equipment and could give me a good idea on where to start. Here's what I have right now.

Mic's - Groove Tubes GT55(like) & Studio Projects C1(don't like)

Preamps - Studio Projects VTB-1(like), Presonus Blue Tube (O.K.), & Presonus VXP(don't like)

Soundcard - M-Audio Delta 44

Software - Cakewalk Sonar 1

I'm kind of fishing for ideas since buying new mic's and preamps hasn't really made a big difference. I'm thinking that maybe I need to upgrade the soundcard or software might be nessessary before I go out and invest five hundred bucks in a Grace 101 or RNP preamp.

The biggest problem is that I get great recordings when I simply play guitar and sing simultaneously into one microphone but then lose clarity, expecially vocals, when I attemp to recording everything on separate tracks and mix them down. If anyone knows what upgrade in my setup could improve this probblem the most it would greatly appreciated.

I too would vote for the software upgrade. Sonar 6 PE has some great features and plugins.

Ive gotten some pretty dang good recordings on a Delta44. If its the mix problem you're having, a upgrade of Sonar is your best bet.

If you can find a good deal on an old (new in the box) Sonar PE5, that would be my choice. It has the 64bit engine and some nice plugins that do not come with the studio edition. It also would allow you to upgrade within the PE line for less $$$ down the road.